Touch panel

ABSTRACT

To provide a thin touch panel, a touch panel having a simple structure, a touch panel which can be easily incorporated into an electronic device, or a touch panel with a small number of components. The touch panel includes pixel electrodes arranged in a matrix, a plurality of signal lines, a plurality of scan lines, a plurality of first wirings extending in a direction parallel to the signal lines, and a plurality of second wirings extending in a direction parallel to the scan line. Part of the first wiring and part of the second wiring function as a pair of electrodes included in a touch sensor. The first wiring and the second wiring each have a stripe shape or form a mesh shape and are each provided between two adjacent pixel electrodes in a plan view.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One embodiment of the present invention relates to an input device. Oneembodiment of the present invention relates to a display device. Oneembodiment of the present invention relates to an input/output device.One embodiment of the present invention relates to a touch panel.

Note that one embodiment of the present invention is not limited to theabove technical field. Examples of the technical field of one embodimentof the present invention disclosed in this specification and the likeinclude a semiconductor device, a display device, a light-emittingdevice, a power storage device, a memory device, an electronic device, alighting device, an input device, an input/output device, a drivingmethod thereof, and a manufacturing method thereof.

In this specification and the like, a semiconductor device generallymeans a device that can function by utilizing semiconductorcharacteristics. A semiconductor element such as a transistor, asemiconductor circuit, an arithmetic device, and a memory device areeach an embodiment of a semiconductor device. An imaging device, adisplay device, a liquid crystal display device, a light-emittingdevice, an input device, an input/output device, an electro-opticaldevice, a power generation device (including a thin film solar cell, anorganic thin film solar cell, and the like), and an electronic devicemay each include a semiconductor device.

2. Description of the Related Art

In recent years, a display device provided with a touch sensor as aposition-input device has been in practical use. For example, a displaydevice provided with a touch sensor is called a touch panel, a touchscreen, or the like. Examples of a portable information terminalprovided with a touch panel are a smartphone and a tablet terminal.

As one of display devices, there is a liquid crystal display deviceprovided with a liquid crystal element. For example, an active matrixliquid crystal display device, in which pixel electrodes are arranged ina matrix and transistors are used as switching elements connected torespective pixel electrodes, has attracted attention.

For example, an active matrix liquid crystal display device includingtransistors, in which metal oxide is used for a channel formationregion, as switching elements connected to respective pixel electrodesis already known (Patent Documents 1 and 2).

It is known that a liquid crystal display device is classified into twomajor types: transmissive type and reflective type.

In a transmissive liquid crystal display device, a backlight such as acold cathode fluorescent lamp or an LED is used, and a state in whichlight from the backlight is transmitted through liquid crystal andoutput to the outside of the liquid crystal display device or a state inwhich light is not output is selected using optical modulation action ofliquid crystal, whereby bright and dark images are displayed.Furthermore, those displays are combined to display an image.

In a reflective liquid crystal display device, a state in which externallight, that is, incident light is reflected at a pixel electrode andoutput to the outside of the device or a state in which incident lightis not output to the outside of the device is selected using opticalmodulation action of liquid crystal, whereby bright and dark images aredisplayed. Furthermore, those displays are combined to display an image.

Examples of the display device include a light-emitting device includinga light-emitting element such as an organic electroluminescent (EL)element or a light-emitting diode (LED), and an electronic paperperforming display by an electrophoretic method or the like.

Patent Document 3 discloses a flexible light-emitting device in which anorganic EL element is used.

REFERENCE Patent Document

[Patent Document 1] Japanese Published Patent Application No.2007-123861

[Patent Document 2] Japanese Published Patent Application No.2007-096055

[Patent Document 3] Japanese Published Patent Application No.2014-197522

SUMMARY OF THE INVENTION

What is desirable is a touch panel in which a display panel is providedwith a function of inputting data with a finger, a stylus, or the liketouching a screen as a user interface.

Furthermore, it is demanded that an electronic appliance using a touchpanel is reduced in thickness and weight. Therefore, a touch panelitself is required to be reduced in thickness and weight.

For example, in a touch panel, a substrate provided with a touch sensorcan be attached to the display surface side of a display panel. However,in such a structure, the thickness of the touch panel cannot be reducedand the number of components is increased.

One object of one embodiment of the present invention is to provide athin touch panel. Another object is to provide a touch panel having asimple structure. Another object is to provide a touch panel which canbe easily incorporated into an electronic device. Another object is toprovide a touch panel with a small number of components. Another objectis to provide a lightweight touch panel. Another object is to provide atouch panel with high detection sensitivity.

Another object is to provide a novel input device. Another object is toprovide a novel input device, a novel output device, a novelinput/output device, or the like. Note that the description of theseobjects does not disturb the existence of other objects. In oneembodiment of the present invention, there is no need to achieve all theobjects. Other objects can be derived from the description of thespecification, the drawings, the claims, and the like.

One embodiment of the present invention is a touch panel including adisplay portion, a signal line, a scan line, a first wiring, and asecond wiring. The display portion includes a plurality of pixelelectrodes. The plurality of pixel electrodes are arranged in a firstdirection and a second direction intersecting the first direction in amatrix. The signal line extends in the first direction. The scan lineextends in the second direction. The first wiring extends in the firstdirection. The second wiring extends in the second direction. The firstwiring includes a first portion parallel to the signal line, and thefirst portion is between two pixel electrodes adjacent in the seconddirection in a plan view. The second wiring includes a second portionparallel to the scan line, and the second portion is between two pixelelectrodes adjacent in the first direction in a plan view.

In the above, it is preferable that the first wiring do not intersectthe signal line in a portion overlapping with the display portion andthe second wiring do not intersect the scan line in a portionoverlapping with the display portion. In that case, it is preferablethat the signal line and the first wiring be formed by processing thesame conductive film and the scan line and the second wiring be formedby processing the same conductive film.

Alternatively, it is preferable that the first wiring be formed byprocessing the same conductive film as the signal line, and the secondwiring include a third portion formed by processing the same conductivefilm as the signal line and a fourth portion formed by processing thesame conductive film as the scan line. In that case, the fourth portionpreferably intersects the signal line or the first wiring.

Alternatively, it is preferable that the second wiring be formed byprocessing the same conductive film as the scan line and the firstwiring include a fifth portion formed by processing the same conductivefilm as the signal line and a sixth portion formed by processing thesame conductive film as the scan line. In that case, the fifth portionpreferably intersects the scan line or the second wiring.

Alternatively, the first wiring preferably includes a seventh portionparallel to the scan line and intersecting the signal line. In thatcase, the seventh portion is preferably between two pixel electrodesadjacent in the first direction. The second wiring preferably includesan eighth portion parallel to the signal line and intersecting the scanline. The eighth portion is preferably between two pixel electrodesadjacent in the second direction.

In that case, the first wiring preferably has a mesh shape surroundingone or more of the pixel electrodes in a plan view. The second wiringpreferably has a mesh shape surrounding another one or more of the pixelelectrodes in a plan view.

In the above, the first portion of the first wiring, the eighth portionof the second wiring, and the signal line are preferably formed byprocessing the same conductive film. The seventh portion of the firstwiring, the second portion of the second wiring, and the scan line arepreferably formed by processing the same conductive film.

In the above, one of the first wiring and the second wiring ispreferably formed by processing the same conductive film as the scanline or the signal line. The other of the first wiring and the secondwiring is preferably formed by processing a conductive film differentfrom the scan line and the signal line. In that case, the other of thefirst wiring and the second wiring is preferably formed by processingthe same conductive film as the pixel electrode.

Alternatively, in the above, the first wiring is preferably formed byprocessing a conductive film different from the scan line and the signalline. The second wiring is preferably formed by processing a conductivefilm different from the scan line and the signal line. In that case, thefirst wiring or the second wiring, or the first wiring and the secondwiring are preferably formed by processing the same conductive film asthe pixel electrode.

In the above, the touch panel preferably includes a liquid crystalelement including a pixel electrode, a liquid crystal, and a commonelectrode.

In that case, the touch panel preferably includes a first substrate, asecond substrate, a first polarizing plate, a second polarizing plate,and a backlight. The backlight, the first polarizing plate, the firstsubstrate, the second substrate, and the second polarizing plate arepreferably stacked in this order. In that case, the signal line, thescan line, the first wiring, the second wiring, and the pixel electrodeare preferably provided on the second substrate side of the firstsubstrate.

Alternatively, in the above, the touch panel preferably includes alight-emitting element including a pixel electrode, an EL layer, and acommon electrode.

In that case, the touch panel preferably includes a first substrate, asecond substrate, and a polarizing plate. The polarizing plate, thefirst substrate, and the second substrate are preferably stacked in thisorder. In that case, the signal line, the scan line, the first wiring,the second wiring, and the pixel electrode are preferably provided onthe second substrate side of the first substrate.

In this specification and the like, a display panel has a function ofdisplaying or outputting an image or the like on or to a displaysurface. Thus, the display panel is one embodiment of an output device.

In this specification and the like, a structure in which a connectorsuch as a flexible printed circuit (FPC) or a tape carrier package (TCP)is attached to a substrate of a display panel, or a structure in whichan integrated circuit (IC) is mounted on a substrate by a chip on glass(COG) method is referred to as a display panel module or a displaymodule, or simply referred to as a display panel or the like in somecases.

In this specification and the like, a touch sensor has a function ofsensing the contact or approach of an object such as a finger or astylus. Therefore, the touch sensor is one embodiment of an outputdevice.

In this specification and the like, a substrate including a touch sensoris referred to as a touch sensor panel or simply referred to as a touchsensor or the like in some cases. Furthermore, in this specification andthe like, a structure in which a connector such as an FPC or a TCP isattached to a substrate of a touch sensor panel, or a structure in whichan integrated circuit (IC) is mounted on a substrate by a COG method isreferred to as a touch sensor panel module, a touch sensor module, or asensor module, or simply referred to as a touch sensor or the like insome cases.

Note that in this specification and the like, a touch panel has afunction of displaying or outputting an image or the like on or to adisplay surface and a function as a touch sensor capable of detectingthe contact or approach of an object such as a finger or a stylus on orto the display surface. Therefore, the touch panel is an embodiment ofan input/output device.

A touch panel can be referred to, for example, a display panel (ordisplay device) with a touch sensor or a display panel (or displaydevice) having a touch sensor function.

A touch panel can include a display panel and a touch sensor panel.Alternatively, a touch panel can have a function of a touch sensorinside a display panel.

In this specification and the like, a structure in which a connectorsuch as an FPC or a TCP is attached to a substrate of a touch panel, ora structure in which an integrated circuit (IC) is mounted on asubstrate by a COG method is referred to as a touch panel module, adisplay module, or simply referred to as a touch panel or the like insome cases.

According to one embodiment of the present invention, a thin touch panelcan be provided. Alternatively, a touch panel with a simple structurecan be provided. Alternatively, a touch panel which can be easilyincorporated into an electronic device. Alternatively, a touch panelwith a small number of components can be provided. Alternatively, alightweight touch panel can be provided.

One embodiment of the present invention does not necessarily achieve allthe effects listed above. Other effects will be apparent can be derivedfrom the description of the specification, the drawings, the claims, andthe like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B show a structure example of a touch panel module of anembodiment.

FIGS. 2A to 2C each show a structure example of a touch panel module ofan embodiment.

FIGS. 3A to 3C each show a structure example of a touch panel module ofan embodiment.

FIGS. 4A to 4C each show a structure example of a touch panel module ofan embodiment.

FIGS. 5A to 5C each show a structure example of a touch panel module ofan embodiment.

FIGS. 6A and 6B each illustrate structural examples of wirings of anembodiment.

FIGS. 7A and 7B each illustrate structural examples of wirings of anembodiment.

FIG. 8 shows a structure example of a touch panel module of anembodiment.

FIGS. 9A and 9B each show a structure example of a touch panel module ofan embodiment.

FIGS. 10A and 10B each show a structure example of a touch panel moduleof an embodiment.

FIGS. 11A and 11B each show a structure example of a touch panel moduleof an embodiment.

FIGS. 12A and 12B each show a structure example of a touch panel moduleof an embodiment.

FIG. 13 shows a structure example of a touch panel module of anembodiment.

FIGS. 14A and 14B each show a structure example of a touch panel moduleof an embodiment.

FIGS. 15A and 15B each show a structure example of a touch panel moduleof an embodiment.

FIG. 16 shows a structure example of a touch panel module of anembodiment.

FIG. 17 shows a structure example of a touch panel module of anembodiment.

FIGS. 18A and 18B each show a structure example of a pixel of anembodiment.

FIG. 19 shows a structure example of a pixel of an embodiment.

FIG. 20 shows a structure example of a pixel of an embodiment.

FIG. 21 shows a structure example of a touch panel module of anembodiment.

FIGS. 22A and 22B each show a structure example of a touch panel moduleof an embodiment.

FIG. 23 shows a structure example of a touch panel module of anembodiment.

FIGS. 24A and 24B each show a structure example of a touch panel moduleof an embodiment.

FIGS. 25A and 25B each show a structure example of a touch panel moduleof an embodiment.

FIG. 26 shows a structure example of a touch panel module of anembodiment.

FIGS. 27A and 27B each show a structure example of a touch panel moduleof an embodiment.

FIGS. 28A and 28B each show a structure example of a touch panel moduleof an embodiment.

FIG. 29 shows a configuration example of a circuit of an embodiment.

FIG. 30 shows a configuration example of a circuit of an embodiment.

FIG. 31 shows a structure example of a touch panel module of anembodiment.

FIG. 32 shows a structure example of a touch panel module of anembodiment.

FIG. 33 shows a structure example of a touch panel module of anembodiment.

FIG. 34 shows a structure example of a touch panel module of anembodiment.

FIG. 35 shows a structure example of a touch panel module of anembodiment.

FIG. 36 shows a structure example of a touch panel module of anembodiment.

FIG. 37 shows a structure example of a touch panel module of anembodiment.

FIG. 38 shows a structure example of a touch panel module of anembodiment.

FIG. 39 shows a structure example of a touch panel module of anembodiment.

FIG. 40 shows a structure example of a touch panel module of anembodiment.

FIG. 41 shows a structure example of a touch panel module of anembodiment.

FIG. 42 shows a structure example of a touch panel module of anembodiment.

FIGS. 43A and 43B are a circuit diagram and a timing chart of a touchsensor of an embodiment.

FIGS. 44A1, 44A2, 44B1, 44B2, 44C1, and 44C2 are cross-sectional viewseach illustrating an embodiment of a transistor.

FIGS. 45A1, 45A2, 45A3, 45B1, and 45B2 are cross-sectional views eachillustrating an embodiment of a transistor.

FIGS. 46A1, 46A2, 46A3, 46B1, 46B2, 46C1, and 46C2 are cross-sectionalviews each illustrating an embodiment of a transistor.

FIG. 47 is a block diagram of a touch panel module of an embodiment.

FIGS. 48A to 48C each show a structure example of a touch panel moduleof an embodiment.

FIG. 49 illustrates a display module of an embodiment.

FIGS. 50A to 50H each illustrate an electronic device of an embodiment.

FIGS. 51A and 51B each illustrate an electronic device of an embodiment.

FIGS. 52A, 52B, 52C1, 52C2, 52D, 52E, 52F, 52G, and 52H each illustratean electronic device of an embodiment.

FIGS. 53A1, 53A2, 53B, 53C, 53D, 53E, 53F, 53G, 53H, and 53I eachillustrate an electronic device of an embodiment.

FIGS. 54A to 54E illustrate electronic devices of embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments will be described in detail with reference to drawings. Notethat the present invention is not limited to the description below, andit is easily understood by those skilled in the art that various changesand modifications can be made without departing from the spirit andscope of the present invention. Accordingly, the present inventionshould not be interpreted as being limited to the content of theembodiments below.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. Furthermore, the same hatching pattern isapplied to portions having similar functions, and the portions are notespecially denoted by reference numerals in some cases.

Note that in each drawing described in this specification, the size, thelayer thickness, or the region of each component is exaggerated forclarity in some cases. Therefore, embodiments of the present inventionare not limited to such a scale.

Note that in this specification and the like, ordinal numbers such as“first”, “second”, and the like are used in order to avoid confusionamong components and do not limit the number.

Embodiment 1

In this embodiment, a structure example of a touch panel of oneembodiment of the present invention will be described with reference todrawings. Specifically, an example where a capacitive touch sensor isused for the touch panel of one embodiment of the present invention willbe described below.

Examples of the capacitive touch sensor are a surface capacitive touchsensor and a projected capacitive touch sensor. Examples of a projectedcapacitive touch sensor are a self-capacitive touch sensor and a mutualcapacitive touch sensor. The use of a mutual capacitive touch sensor ispreferable because multiple points can be detected simultaneously.

The touch sensor that can be used for the touch panel of one embodimentof the present invention includes a pair of conductive layers.Capacitive coupling is generated in the pair of conductive layers. Thecapacitance of the pair of conductive layers changes when an objecttouches or approaches the pair of conductive layers. Utilizing thiseffect, detection can be conducted.

The touch panel of one embodiment of the present invention includespixels arranged in a matrix, a plurality of signal lines, and aplurality of scan lines. The pixel includes a pixel electrode. Thesignal lines and the scan lines are provided to extend in directionsintersecting each other. Here, a direction in which the signal linesextend is referred to as a first direction or an X direction, and adirection in which the scan lines extend is referred to as a seconddirection or a Y direction. It is acceptable as long as the firstdirection and the second direction intersect each other; however, theyare preferably orthogonal to each other.

In addition, the touch panel of one embodiment of the present inventionincludes a plurality of first wirings extending in the first directionand a plurality of second wirings extending in the second direction.Part of the first wiring and part of the second wiring function as apair of electrodes included in the touch sensor. In other words,capacitive coupling occurs between the first wiring and the secondwiring.

In this specification and the like, “a layer, a wiring, a structure, orthe like extends in a direction” means that the layer, the wiring, thestructure, or the like is provided to extend in the direction. When seenfrom the above, the layer, the wiring, the structure, or the like mayhave a long extending shape in the direction, and may partly have aportion extending in a direction different from the direction.

The first wiring and the second wiring each can be provided between twoadjacent pixel electrodes in a plan view. In this case, part of thefirst wiring and part of the second wiring may overlap with the pixelelectrode.

The pair of wirings included in the touch sensor are provided in aregion other than an optical path of light from a display element; thus,moire is not generated in principle. Here, moire means interferencefringes generated in the case where two or more regular patterns overlapwith each other. As a result, a touch panel having extremely highdisplay quality can be obtained.

It is preferable that a light-blocking layer or a circularly polarizingplate be provided closer to the display surface side than the pair ofwirings included in the touch sensor are. This can reduce or preventreflection of external light caused by the pair of wirings, and the pairof wirings are less likely to be recognized by a user.

For example, the first wiring and the second wiring each can have ashape extending in the first direction or the second direction in theform of stripes. In that case, some of the plurality of first wiringsare electrically connected to each other in a region outside the displayportion that displays an image to form a group. Similarly, some of theplurality of second wirings are electrically connected to each other ina region outside the display portion to form a group. With such astructure, an area which contributes to detection in the first wiringand the second wiring is increased, so that the detection sensitivitycan be increased.

As another example, the first wiring and the second wiring each can havea mesh shape including portions parallel to the first direction and thesecond direction. In that case, one or more pixel electrodes can beprovided in an opening of the mesh in a plan view. When the first wiringand the second wiring each have a mesh shape, the conductivity in theextending directions can be increased, so that delay of signals can besuppressed; thus, the detection sensitivity can be increased.

Here, the first wiring and the second wiring are preferably formed byprocessing the same film as a wiring, an electrode, a semiconductor, orthe like included in the pixel or the display element of the touchpanel, a driver circuit, or the like. Thus, a touch panel can bemanufactured without providing a special step for adding a function of atouch sensor, which leads to a reduction in manufacturing cost.

Typically, in the case where the first wiring and the second wiring eachhave a stripe shape as described above, for example, the first wiringcan be formed by processing the same conductive film as the signal lineand the second wiring can be formed by processing the same conductivefilm as the scan line. Thus, the first wiring and the second wiring canbe formed over different insulating layers, so that the first wiring andthe second wiring can intersect each other without a specialcontrivance. Since the first wiring and the scan line are formed overdifferent insulating layers and the second wiring and the signal lineare formed over different insulating layers in that case, the firstwiring and the scan line, or the second wiring and the signal line canintersect each other without a special contrivance.

For example, in the case where the first wiring and the second wiringeach have a mesh shape as described above, the mesh shape can be formedin such a manner that portions parallel to the first direction areformed by processing the same conductive film as the signal line andportions parallel to the second direction are formed by processing thesame conductive film as the scan line and these two types of portionsare electrically connected to each other. Thus, arbitrary two of thefirst wiring, the second wiring, the signal line, and the scan line canintersect each other without a special contrivance.

Note that the structures of the first wiring and the second wiring arenot limited thereto. Other examples are described later.

In the case where the first wiring and the second wiring are formed byprocessing the same film as a wiring, an electrode, a semiconductorlayer, or the like included in the pixel or the display element of thetouch panel, the driver circuit, or the like, when the side of asubstrate over which the first wiring and the second wiring are formed(also referred to as a first substrate or an element substrate)functions as a touch surface, the first wiring and the second wiring canbe close to the touch surface; thus, higher sensitivity can bepreferably obtained. In that case, the first substrate side of the touchpanel functions as a display surface. In the case where a transmissiveliquid crystal display device is used as the display element, forexample, a polarizing plate and a backlight can be provided outside asubstrate which is provided to face the first substrate and seals liquidcrystal (also referred to as a second substrate or a counter substrate)and a polarizing plate can be provided outside the first substrate. Abottom emission light-emitting element can be used as the displayelement, for example.

A more specific structure example of one embodiment of the presentinvention is described below with reference to drawings.

[Structure Example]

FIG. 1A is a schematic perspective view of a touch panel module 10 ofone embodiment of the present invention. In the touch panel module 10, asubstrate 21 and a substrate 31 are attached to each other.

FIG. 1B illustrates a structure of the substrate 21, and the substrate31 is denoted by a broken line. A display portion 32 including aplurality of pixel circuits, a circuit 34, a wiring 35, and the like areprovided over the substrate 21. An IC 43 and an FPC 42 are mounted overthe substrate 31.

FIG. 1B is an enlarged view of part of the display portion 32. Thedisplay portion 32 includes a plurality of signal lines 51 extending inthe X direction, a plurality of scan lines 52 extending in the Ydirection, and a plurality of pixel electrodes 36 arranged in the Xdirection and the Y direction in a matrix. Furthermore, a plurality ofwirings 23 extending in the X direction and a plurality of wirings 24extending in the Y direction are provided in the display portion 32. Thewiring 23 includes a portion parallel to the signal line 51 and thewiring 24 includes a portion parallel to the scan line 52.

The wiring 23 and the wiring 24 function as a pair of electrodesincluded in the touch sensor.

As described above, the touch panel module 10 of one embodiment of thepresent invention includes a pair of wirings functioning as electrodesof the touch sensor over a substrate over which the pixel electrode 36,the signal line 51, the scan line 52, and the like are provided. Thus,the pair of wirings of the touch sensor can be formed through the samesteps as the pixel electrode 36, the signal line 51, the scan line 52,or the like which are used to display an image, so that manufacturingcost can be reduced.

Capacitive coupling occurs between the wiring 23 and the wiring 24. Forexample, in the case of employing a projected mutual-capacitive drivingmethod, one of the wirings 23 and 24 can be used as a transmission-sidewiring (electrode), and the other thereof can be used as areception-side wiring (electrode). In the case of employing a projectedself-capacitive driving method, each of the wiring 23 and the wiring 24can serve as both a transmission wiring and a reception wiring.

The wiring 23 and the wiring 24 are preferably formed by processing thesame film as the signal line 51, the scan line 52, the pixel electrode36, or a wiring, an electrode, a semiconductor, or the like provided inthe display portion 32, for example.

For example, a low-resistance material is preferably used as a materialof the wirings 23 and 24. As an example, metal such as silver, copper,or aluminum may be used. Alternatively, a metal nanowire including anumber of conductors with an extremely small width (for example, adiameter of several nanometers) may be used. Examples of such a metalnanowire include an Ag nanowire, a Cu nanowire, and an Al nanowire. Inthe case of using an Ag nanowire, light transmittance of 89% or more anda sheet resistance of 40 ohm/square or more and 100 ohm/square or lesscan be achieved. Note that because such a metal nanowire provides hightransmittance, the metal nanowire may be used for an electrode of thedisplay element, e.g., a pixel electrode or a common electrode.

Alternatively, conductive oxide can be used for at least one of thewiring 23 and the wiring 24. For example, a conductive materialcontaining indium oxide, tin oxide, or zinc oxide may be used. In thecase where a material that transmits visible light is used for thewiring 23 or the wiring 24, the wiring and a display element may beprovided to overlap with each other and light from the display elementmay be emitted through the wiring. In other words, in the case where amaterial that transmits visible light is used, the wiring may beprovided to overlap with the pixel electrode 36.

A display element in which the pixel electrode 36 is used as anelectrode can be applied to the display portion 32. Here, alight-emitting element such as a transmissive liquid crystal displayelement or an organic EL element can be preferably used as the displayelement.

Note that the display element is not limited thereto, and a variety ofelements can be used. Examples of the display element include reflectiveor semi-transmissive liquid crystal elements; display elements(electronic ink) that perform display by an electrophoretic method, anelectronic liquid powder (registered trademark) method, or the like;MEMS shutter display elements; and optical interference type MEMSdisplay elements. A pixel included in the display portion 32 may includea pixel circuit in addition to the display element. The pixel circuitmay have a transistor, a capacitor, a wiring that electrically connectsthe transistor and the capacitor, and the like, for example.

[Cross-Sectional Structure Example 1]

FIG. 2A is a schematic cross-sectional view of part of the displayportion 32. FIG. 2A illustrates an example of one pixel, the wiring 23,and the wiring 24. Here, an example where a liquid crystal element isused as a display element provided in the pixel is shown.

Although not illustrated here, in the touch panel module 10, thesubstrate 21 and the substrate 31 are attached to each other with anadhesive layer or the like in a peripheral portion. Furthermore, aliquid crystal 37 is sealed between the substrate 21 and the substrate31.

In the display portion 32, a transistor 70, the pixel electrode 36, thewiring 23, the wiring 24, and the like are provided over the substrate21. A coloring layer 65, a light-blocking layer 66, a common electrode38, and the like are provided on the side of a surface of the substrate31 which faces the substrate 21.

The transistor 70 includes a conductive layer 71 functioning as a gate,a semiconductor layer 72, an insulating layer 73 functioning as a gateinsulating layer, a conductive layer 74 a functioning as one of a sourceand a drain, a conductive layer 74 b functioning as the other of thesource and the drain, and the like.

As an example, the conductive layer 74 a is part of the signal line 51and the conductive layer 71 is part of the scan line 52.

An insulating layer 81 is provided to cover the transistor 70, and thepixel electrode 36 is provided over the insulating layer 81. The pixelelectrode 36 is electrically connected to the conductive layer 74 bthrough an opening in the insulating layer 81. The liquid crystalelement 60 includes the pixel electrode 36, the common electrode 38, andthe liquid crystal 37 sandwiched therebetween. In FIG. 2A, the liquidcrystal element 60 is a transmissive liquid crystal element using avertical alignment (VA) mode.

Here, as for the liquid crystal element 60, a pair of electrodes areprovided in the thickness direction of the touch panel module 10 and anelectric field is applied to the liquid crystal 37 in the thicknessdirection. The arrangement of the electrodes is not limited thereto, anda method in which an electric field is applied in a directionperpendicular to the thickness direction may be employed.

Furthermore, a normally black liquid crystal display device, forexample, a transmissive liquid crystal display device using a verticalalignment (VA) mode can be used as the touch panel module 10. Examplesof the vertical alignment mode include a multi-domain vertical alignment(MVA) mode, a patterned vertical alignment (PVA) mode, and an advancedsuper view (ASV) mode.

Liquid crystal elements using a variety of modes can be used as theliquid crystal element 60. For example, a liquid crystal element using,instead of a VA mode, a twisted nematic (TN) mode, an in-plane switching(IPS) mode, a fringe field switching (FFS) mode, an axially symmetricaligned micro-cell (ASM) mode, an optically compensated birefringence(OCB) mode, a ferroelectric liquid crystal (FLC) mode, anantiferroelectric liquid crystal (AFLC) mode, or the like can be used.

The liquid crystal element controls transmission or non-transmission oflight utilizing an optical modulation action of liquid crystal. Notethat optical modulation action of liquid crystal is controlled by anelectric field applied to the liquid crystal (including a horizontalelectric field, a vertical electric field, or an oblique electricfield). As the liquid crystal used for the liquid crystal element,thermotropic liquid crystal, low-molecular liquid crystal,high-molecular liquid crystal, polymer dispersed liquid crystal (PDLC),ferroelectric liquid crystal, anti-ferroelectric liquid crystal, or thelike can be used. These liquid crystal materials exhibit a cholestericphase, a smectic phase, a cubic phase, a chiral nematic phase, anisotropic phase, or the like depending on conditions.

As the liquid crystal material, either of a positive liquid crystal anda negative liquid crystal may be used, and an appropriate liquid crystalmaterial can be used depending on the mode or design to be used.

FIG. 2A illustrates an example where the wiring 24 and the conductivelayer 71 are formed by processing the same conductive film and providedon the same surface. Furthermore, the wiring 23, the conductive layer 74a, and the conductive layer 74 b are formed by processing the sameconductive film and provided on the same surface. Here, the wiring 23 isformed over the insulating layer 73, and the wiring 24 is formed overthe substrate 21 having an insulating property. Since the insulatinglayer 73 is provided between the wiring 23 and the wiring 24, thewirings 23 and 24 can intersect each other without a specialcontrivance.

As illustrated in FIG. 2A, capacitive coupling occurs between the wiring23 and the wiring 24. For example, in the case of employing a projectedcapacitive driving method, one of the wirings 23 and 24 can be used as atransmission-side electrode, and the other thereof can be used as areception-side electrode.

A polarizing plate 61 and a polarizing plate 62 are provided so that thesubstrate 21 and the substrate 31 are sandwiched therebetween. Abacklight 63 is provided outside the polarizing plate 62. Thus, lightenters from the backlight in a direction shown by an arrow in FIG. 2A,and the substrate 21 side functions as the display surface side.

As the backlight 63, a direct-below backlight or an edge-light backlightmay be used. When a direct-below backlight including a light-emittingdiode (LED) is used, local dimming is easily performed; thus, contrastcan be preferably increased. When an edge-light type backlight is used,the thickness of a touch panel module including the backlight can bepreferably reduced.

As the polarizing plate 61 on the display surface side, a linearpolarizing plate or a circularly polarizing plate can be used. As thecircularly polarizing plate, for example, a stack including a linearpolarizing plate and a quarter-wave retardation plate can be used. Inparticular, as illustrated in FIGS. 2A to 2C, in the case where thewiring 23 and the wiring 24 included in the touch sensor are provided onthe substrate 21 side, external light is reflected by the wirings andthe reflected light is visually recognized in some cases. In this case,reflection can be suppressed with a circularly polarizing plate used asthe polarizing plate 61.

In the case where a circularly polarizing plate is used as thepolarizing plate 61, a circularly polarizing plate may be also used asthe polarizing plate 62 and a general linear polarizing plate may beused. The cell gap, alignment, driving voltage, and the like of theliquid crystal element 60 are controlled depending on the kinds ofpolarizing plates used as the polarizing plates 61 and 62 so thatdesirable contrast is obtained.

The coloring layer 65 can also be referred to as a color filter, andconverts light of the backlight 63 into light exhibiting a specificcolor. For example, the coloring layer 65 of red, green, or blue isprovided as a coloring layer in each pixel (sub-pixel); thus, full-colordisplay can be performed. When a pixel (sub-pixel) corresponding toyellow, white, or the like in addition to the three colors is provided,power consumption can be reduced, which is preferable.

In the case where a transmissive liquid crystal element is used as theliquid crystal element 60, a light-transmitting conductive film can beused as the pixel electrode 36 and the common electrode 38. In the casewhere a reflective liquid crystal element is used, a light-reflectingmaterial can be used for the pixel electrode 36 or the common electrode38.

In the liquid crystal element 60 in FIG. 2A, the pixel electrode 36 andthe common electrode 38 have a function of transmitting visible light.By having such a structure, the liquid crystal element 60 can be atransmissive liquid crystal element. For example, in the case where thebacklight 63 is positioned on the substrate 31 side, light from thebacklight 63 which is polarized by the polarizing plate 62 passesthrough the substrate 31, the common electrode 38, the liquid crystal37, the pixel electrode 36, the substrate 21, and the like, and thenreaches the polarizing plate 61. In this case, alignment of the liquidcrystal 37 is controlled with a voltage applied between the pixelelectrode 36 and the common electrode 38, and thus, optical modulationof light can be controlled. In other words, the intensity of lightemitted through the polarizing plate 61 can be controlled. Light otherthan one in a particular wavelength region of the incident light isabsorbed by the coloring layer 65, and thus, emitted light has emissionspectrum peak in the particular wavelength region. For example, lightemitted through the polarizing plate 61 becomes light with red, green,or blue.

It is preferable that the transistor 70 be provided to overlap with thelight-blocking layer 66 as illustrated in FIG. 2A. With such astructure, the semiconductor layer 72 of the transistor 70 is preventedfrom being irradiated with light from the backlight 63; thus, thereliability can be increased. Furthermore, it is preferable that thewiring 23 and the wiring 24 be provided to overlap with thelight-blocking layer 66. Thus, irregular reflection of light from thebacklight 63 which is caused by the wiring 23 or the wiring 24 can beprevented, so that contrast of an image or a movie to be displayed canbe increased.

FIG. 2B illustrates an example where both of the wirings 23 and 24 areformed by processing the same conductive film as the conductive layer 74a and the conductive layer 74 b. In that case, a bridge structure isformed in an intersection portion of the wiring 23 and the wiring 24 byusing a conductive layer obtained by processing the same conductive filmas the conductive layer 71, the pixel electrode 36, or the like so thatthe wirings 23 and 24 intersect each other. For example, the conductivelayer may be provided to overlap with one of the wirings 23 and 24 andelectrically connected to the other thereof.

FIG. 2C illustrates an example where both of the wirings 23 and 24 areformed by processing the same conductive film as the conductive layer71. In that case, in the same manner as the above, a bridge structure isformed in an intersection portion of the wiring 23 and the wiring 24 byusing a conductive layer obtained by processing the same conductive filmas the conductive layer 74 a, the pixel electrode 36, or the like.

Although the transistor 70 is a bottom-gate transistor in each of FIGS.2A to 2C, a top-gate transistor may be used.

FIG. 3A illustrates an example where the transistor 70 is a top-gatetransistor.

The transistor 70 in FIG. 3A includes the semiconductor layer 72, theinsulating layer 73 covering the semiconductor layer 72, and theconductive layer 71 overlapping with part of the semiconductor layer 72.The semiconductor layer 72 includes a pair of low-resistance regions 75between which a region where a channel is formed (a region overlappingwith the conductive layer 71) is interposed. One of the low-resistanceregions 75 functions as a source and the other thereof functions as adrain. The conductive layer 74 a and the conductive layer 74 b areelectrically connected to the respective low-resistance regions 75through openings in the insulating layer 81.

As illustrated in FIG. 3A, an insulating layer 82 is provided to coverthe conductive layer 74 a and the conductive layer 74 b, and the pixelelectrode 36 is provided over the insulating layer 82. The pixelelectrode 36 is electrically connected to the conductive layer 74 bthrough an opening in the insulating layer 82.

FIG. 3A illustrates an example where the wiring 23 is formed byprocessing the same conductive film as the conductive layers 74 a and 74b and the wiring 24 is formed by processing the same conductive film asthe conductive layer 71. The wiring 23 is positioned over the insulatinglayer 81 and the wiring 24 is positioned over the insulating layer 73.

FIG. 3B illustrates an example where both of the wirings 23 and 24 areformed by processing the same conductive film as the conductive layer71. Moreover, FIG. 3C illustrates an example where both of the wirings23 and 24 are formed by processing the same conductive film as theconductive layer 74 a and the conductive layer 74 b.

In each of FIGS. 2A to 2C and FIGS. 3A to 3C, the substrate 21 sidefunctions as the display surface side; however, the substrate 31 sidemay function as the display surface side. In that case, the backlight 63is provided outside the polarizing plate 61. Moreover, a circularlypolarizing plate may be used as the polarizing plate 61, or a circularlypolarizing plate may be provided in addition to the polarizing plate 61.

Here, an example where the backlight 63 is provided outside thesubstrate 31 and the substrate 21 side functions as the display surfaceand the touch surface of the touch panel is shown. In particular, whenthe substrate 21 side on which the wiring 23 and the wiring 24 aresupported functions as the touch surface of the touch panel, thephysical distance between an object and the wiring 23 or the wiring 24can be short; thus, the detection sensitivity of the touch sensor can beincreased. Note that one embodiment of the present invention is notlimited thereto, and the backlight 63 can be provided outside thesubstrate 21 and the substrate 31 side can function as the displaysurface and the touch surface of the touch panel.

The above is the description of Cross-sectional Structure Example 1.

[Cross-Sectional Structure Example 2]

An example where a bottom-emission organic EL element is used as adisplay element in a pixel is shown below. Note that portions similar tothose described above are not described in some cases.

FIG. 4A is a schematic cross-sectional view of part of the displayportion 32. FIG. 4A illustrates an example of one pixel, the wiring 23,and the wiring 24. The substrate 21 side of the display portion 32functions as the display surface side.

In the touch panel module 10, the substrate 21 and the substrate 31 areattached to each other with an adhesive layer 68.

The insulating layer 81 is provided to cover the transistor 70, and thepixel electrode 36 is provided over the insulating layer 81. The pixelelectrode 36 is electrically connected to the conductive layer 74 bthrough an opening in the insulating layer 81. The insulating layer 83is provided over the insulating layer 81. The insulating layer 83includes an opening overlapping with the pixel electrode 36. Part of theinsulating layer 83 is provided to cover an end portion of the pixelelectrode 36. An EL layer 47 and a common electrode 48 are stacked inthis order over the insulating layer 83 and the pixel electrode 36. Thelight-emitting element 40 includes the pixel electrode 36, the commonelectrode 48, and the EL layer 47 sandwiched therebetween.

The light-emitting element 40 in FIG. 4A is a bottom-emissionlight-emitting element in which light is emitted to the substrate 21side on which the light-emitting element 40 is supported. Thus, amongthe pair of electrodes of the light-emitting element 40, the pixelelectrode 36 on the substrate 21 side has a function of transmittingvisible light and the common electrode 48 on the substrate 31 side has afunction of reflecting visible light.

In the structure in FIG. 4A, the coloring layer 65 is provided in aposition closer to the substrate 21 side than the light-emitting element40 is.

The coloring layer 65 converts light from the light-emitting element 40into light having a specific color. For example, when a light-emittingelement emitting white light is used as the light-emitting element 40,the coloring layer 65 of red, green, or blue is provided as a coloringlayer in each pixel (sub-pixel); thus, full-color display can beperformed. When a pixel (sub-pixel) corresponding to yellow, white, orthe like in addition to the three colors is provided, power consumptioncan be reduced, which is preferable.

The structure of the light-emitting element 40 is not limited thereto,and a top-emission light-emitting element or a dual-emissionlight-emitting element can be used. The EL layer 47 of thelight-emitting element 40 is separately fabricated in each pixel(sub-pixel), and thus, the light-emitting elements 40 exhibitingdifferent colors may be separately fabricated in pixels (sub-pixels). Inthat case, the coloring layer 65 is not necessarily provided.

FIG. 4A illustrates an example where the polarizing plate 61 is providedoutside the substrate 21, i.e., on the display surface side. As thepolarizing plate 61, a circularly polarizing plate can be preferablyused. The circularly polarizing plate used as the polarizing plate 61can prevent reflection due to the wiring 23, the wiring 24, or the like.

FIG. 4B illustrates an example where both of the wirings 23 and 24 areformed by processing the same conductive film as the conductive layer 74a and the conductive layer 74 b. FIG. 4C illustrates an example whereboth of the wirings 23 and 24 are formed by processing the sameconductive film as the conductive layer 71.

FIG. 5A illustrates an example where a top-gate transistor is used asthe transistor 70. FIG. 5B illustrates an example where both of thewirings 23 and 24 are formed by processing the same conductive film asthe conductive layer 74 a and the conductive layer 74 b. FIG. 5Cillustrates an example where both of the wirings 23 and 24 are formed byprocessing the same conductive film as the conductive layer 71.

Here, an example where a bottom-emission light-emitting element is usedas the light-emitting element 40 and the substrate 21 side functions asthe display surface and the touch surface of the touch panel is shown.In particular, when the substrate 21 side on which the wiring 23 and thewiring 24 are supported functions as the touch surface of the touchpanel, the physical distance between an object and the wiring 23 or thewiring 24 can be short; thus, the detection sensitivity of the touchsensor can be increased. Note that one embodiment of the presentinvention is not limited thereto, and a top-emission light-emittingelement or a dual-emission light-emitting element can be used as thelight-emitting element 40 and the substrate 31 side may function as thedisplay surface and the touch surface of the touch panel.

[Wiring Shape]

[Example 1 of Wiring Shape]

FIG. 6A illustrates an example of top surface shapes of the wirings 23and the wirings 24. The wirings 23 extend in the X direction and thewirings 24 extend in the Y direction. The wirings 23 each include aplurality of stripes extending in the X direction in a regionoverlapping with the display portion 32, and the plurality of stripesare connected to each other in a region outside the display portion 32.

With such a structure, the wiring 23 can be formed using only portionssubstantially parallel in the X direction and the wiring 24 can beformed using only portions substantially parallel in the Y direction ina portion overlapping with the display portion 32. In that case, sincethe wiring 23 can be arranged not to intersect the signal line 51 (notillustrated) extending in the X direction, they can be formed at thesame time by processing the same conductive film. Similarly, the wiring24 is arranged not to intersect the scan line 52 (not illustrated)extending in the Y direction and they can be formed using the sameconductive film.

As illustrated in FIG. 6B, a conductive layer 26 a extending in the Xdirection may be provided between the adjacent wirings 23. Similarly, aconductive layer 26 b extending in the Y direction may be providedbetween the adjacent wirings 24. The conductive layer 26 a and theconductive layer 26 b can be brought into an electrically floating stateor supplied with a predetermined constant potential, for example.Furthermore, it is preferable in that case that the wiring 23 and theconductive layer 26 a be formed by processing the same conductive filmand that the wiring 24 and the conductive layer 26 b be formed byprocessing the same conductive film. Thus, in the display portion 32, aregular pattern in layout from a region where the wiring 23 and thewiring 24 are provided to a region where they are not provided can bemaintained. Therefore, between a pixel close to the wiring 23 and thewiring 24 and a pixel far from them, luminance unevenness due to athickness difference or the like of stacks included in the pixels can besuppressed.

A short-side direction of the display portion 32 is referred to as the Xdirection and a long-side direction of the display portion 32 isreferred to as the Y direction in FIGS. 6A and 6B and the like; however,one embodiment of the present invention is not limited thereto, and theshort-side direction and the long-side direction may be referred to asthe Y direction and the X direction, respectively.

[Example 2 of Wiring Shape]

FIG. 7A illustrates an example of the wiring 23 and the wiring 24 havingshapes different from those in FIG. 6A.

The wiring 23 and the wiring 24 each have portions parallel in the Xdirection and portions parallel in the Y direction, and a mesh-like topsurface shape can be formed by these two types of portions. In thatcase, the wiring 23 and the wiring 24 are provided so that one or morepixel electrodes 36 (not illustrated) are included in the opening of themesh in a plan view, and accordingly, they can be provided not to blocklight from the display element.

Alternatively, the conductive layer 26 may be provided to fill a spacebetween the wiring 23 and the wiring 24 as illustrated in FIG. 7B. Inthat case, the conductive layer 26 preferably includes portions parallelin the X direction and portions parallel in the Y direction as well asthe wiring 23 and the wiring 24. Moreover, part of the conductive layer26 preferably has a mesh shape.

When the wiring 23 and the wiring 24 are formed by processing differentconductive films over different insulating layers, the wiring 23 and thewiring 24 can intersect each other without a special contrivance.Alternatively, the wiring 24 may have a structure in which anisland-shaped portion formed by processing the same conductive film asthe wiring 23 and an island-shaped portion formed by processing aconductive film over an insulating layer that is different from thewiring 23 are connected to each other so that the wiring 23 and thewiring 24 intersect each other, for example. Alternatively, the wiring23 may have a structure in which such two types of island-shapedportions are connected to each other. Alternatively, the wiring 23 andthe wiring 24 may intersect each other without an electricalshort-circuit in such a manner that at least one of the wirings 23 and24 is formed using portions parallel in the X direction and portionsparallel in the Y direction which are formed by processing differentconductive films over different insulating layers and the two types ofportions are connected to each other.

The above is the description of the wiring shape example.

[Structure Example 1 of Wiring]

A specific structure example of a wiring in the case where a liquidcrystal element is used for the display portion 32 is described below.Note that in the following diagrams, a layer, a wiring, and the likeformed by processing the same conductive film are shown with the samehatching pattern for simplicity.

[Structure Example 1-1]

FIG. 8 illustrates an example of arrangement (layout) of the signal line51, the scan line 52, the wiring 23, the wiring 24, the pixel electrode36, and the like in the display portion 32. FIG. 8 corresponds to anenlarged view of the region A in FIG. 6A or FIG. 7A.

The signal line 51 and the wiring 23 are parallel in the X direction.The scan line 52 and the wiring 24 are parallel in the Y direction. Thesignal line 51 and the wiring 23 are formed by processing the sameconductive film, and the scan line 52 and the wiring 24 are formed byprocessing the same conductive film. Thus, the wiring 23 and the wiring24 can be formed without an increase in the number of steps.

Such a structure enables the wiring 23 and the wiring 24, the signalline 51 and the wiring 24, and the scan line 52 and the wiring 23 tointersect each other without a special contrivance.

FIG. 8 illustrates a pixel circuit 80 including the transistor 70 andthe pixel electrode 36. The pixel circuits 80 are arranged in the Xdirection and the Y direction in a matrix. The pixel circuit 80corresponds to one sub-pixel included in the display portion 32.

In the pixel circuit 80, part of the scan line 52 functions as a gateelectrode. Part of the signal line 51 functions as a source electrode ora drain electrode. As illustrated in FIG. 8, the semiconductor layer 72is provided to overlap with a projected portion of the scan line 52, anda projected portion of the signal line 51 is provided to overlap withpart of the semiconductor layer 72. Furthermore, the conductive layer 74b is provided on a side opposite to the signal line 51 of thesemiconductor layer 72. The conductive layer 74 b is electricallyconnected to the pixel electrode 36.

The wiring 23 is provided between the two pixel circuits 80 adjacent inthe Y direction. It can be said that the wiring 23 is provided betweenthe two pixel electrodes 36 adjacent in the Y direction, between the twosignal lines 51 adjacent in the Y direction, between the twosemiconductor layers 72 adjacent in the Y direction, between the twoconductive layers 74 b adjacent in the Y direction, or the like.

Meanwhile, the wiring 24 is provided between the two pixel circuit 80adjacent in the X direction. It can be said that the wiring 24 isprovided between the two pixel electrodes 36 adjacent in the Xdirection, between the two scan lines 52 adjacent in the X direction,between the two semiconductor layers 72 adjacent in the X direction,between the two conductive layers 74 b adjacent in the X direction, orthe like.

FIG. 8 illustrates an example where the width of the wiring 24 is largerthan that of the wiring 23. For example, in the case where the wiring 24is formed using a material with lower conductivity than a material usedfor the wiring 23, the case where the wiring 24 is arranged along thelong-side direction of the display portion, or the like, the width ofthe wiring 24 is preferably larger than that of the wiring 23 to reduceelectrical resistance. Alternatively, the thickness of the wiring 24 maybe larger than that of the wiring 23 to reduce electrical resistance ofthe wiring 24. Note that the width of the wiring 23 and the width of thewiring 24 are not limited thereto, and that of the wiring 23 may belarger than that of the wiring 24 or those of the wirings 23 and 24 maybe substantially the same. The width, thickness, material, and the likeof each of the wirings 23 and 24 can be appropriately set so that forexample, the time constant of the wiring 23 and that of the wiring 24are substantially the same or one of the wirings 23 and 24 which is usedas a detection-side wiring has a smaller time constant than the other.

[Structure Example 1-2]

FIG. 9A illustrates an example where the structure of the wiring 24 isdifferent from that in FIG. 8. The wiring 24 in FIG. 9A has a structurein which a portion formed by processing the same conductive film as thesignal line 51 and a portion formed by processing the same conductivefilm as the scan line 52 are alternately arranged. The two types ofportions overlap with each other in regions and are electricallyconnected to each other through openings in an insulating layerpositioned therebetween in the regions.

Each of the portions of the wiring 24 that are formed by processing thesame conductive film as the scan line 52 intersects at least one of thesignal line 51 and the wiring 23.

[Structure Example 1-3]

FIG. 9B illustrates an example where the structure of the wiring 23 isdifferent from that in FIG. 8. The wiring 23 in FIG. 9B has a structurein which a portion formed by processing the same conductive film as thesignal line 51 and a portion formed by processing the same conductivefilm as the scan line 52 are alternately arranged. The two types ofportions overlap with each other in regions and are electricallyconnected to each other through openings in an insulating layerpositioned therebetween in the regions.

Each of the portions of the wiring 23 that are formed by processing thesame conductive film as the signal line 51 intersects at least one ofthe scan line 52 and the wiring 24.

Structure Examples 1-1 to 1-3 are preferably used in the case where thewiring 23 and the wiring 24 have a stripe shape in a portion overlappingwith the display portion 32 as illustrated in Example 1 of Wiring Shape(e.g., FIGS. 6A and 6B), for example.

[Structure Example 2-1]

FIG. 10A illustrates an example where the wiring 23 includes both ofportions parallel in the X direction and portions parallel in the Ydirection. FIG. 10B illustrates an example where the wiring 24 includesboth of portions parallel in the X direction and portions parallel inthe Y direction. FIG. 1 OA corresponds to an enlarged view of the regionB in FIG. 7A, and FIG. 10B corresponds to an enlarged view of the regionC in FIG. 7A. Although the wiring 23 is used for the description here,the wiring 24, and the conductive layer 26, the conductive layer 26 a,the conductive layer 26 b, and the like, which are described above canhave similar shapes.

The portions parallel in the X direction in the wiring 23 are formed byprocessing the same conductive film as the signal line 51. Meanwhile,the portions parallel in the Y direction are formed by processing thesame conductive film as the scan line 52. In the wiring 23, the portionsparallel in the X direction are electrically connected to the portionsparallel in the Y direction through openings in an insulating filmpositioned between the two types of portions at the intersections of thetwo types of portions. With such a structure, the wiring 23 can have amesh shape.

Here, it can be said that the wiring 23 has one opening surrounded bytwo portions adjacent and parallel in the X direction and two portionsadjacent and parallel in the Y direction. Although FIGS. 10A and 10Beach illustrate a structure where the three pixel electrodes 36 areprovided in the opening, one embodiment of the present invention is notlimited thereto, and a structure where one or more pixel electrodes 36are provided can be employed. When the wiring 23 has a dense mesh shape,the resistance of the wiring 23 can be reduced. Meanwhile, when thewiring 23 has a sparse mesh shape, parasitic capacitance of the wiring23 can be reduced.

In each of FIGS. 10A and 10B, the distance between the two portionsparallel and adjacent in the X direction in the wiring 23 and thedistance between the two portions parallel and adjacent in the Ydirection in the wiring 23 are set to be substantially the same;however, they may be different from each other. For example, the twoportions parallel and adjacent in the Y direction may be provided with adistance of two pixels (e.g., with a distance of six sub-pixels in thecase where three sub-pixels of RGB are provided) therebetween, and thetwo portions parallel and adjacent in the X direction may be providedwith a distance of one pixel therebetween. In that case, the wiring 23has a mesh shape including an opening which is long in the Y direction.

[Structure Example 2-2]

FIG. 11A illustrates an example where the structure of the wiring 23 isdifferent from those in FIGS. 10A and 10B. In the structure in FIG. 11A,portions parallel in the X direction in the wiring 23 are formed byprocessing the same conductive film as the signal line 51. Meanwhile,portions parallel in the Y direction in the wiring 23 have a structurein which a portion (conductive layer) obtained by processing the sameconductive film as the signal line 51 and a portion (conductive layer)obtained by processing the same conductive film as the scan line 52 arealternately arranged. In the portions parallel in the Y direction, thetwo different conductive layers overlap with each other in regions andare electrically connected to each other through openings in aninsulating layer positioned therebetween in the regions.

In the portions of the wiring 23 which are parallel in the Y direction,the portions obtained by processing the same conductive film as the scanline 52 intersect the signal line 51.

[Structure Example 2-3]

FIG. 11B illustrates an example where the structure of the wiring 23 isdifferent from those in FIGS. 10A and 10B and FIG. 11A. In the structurein FIG. 11B, portions parallel in the Y direction in the wiring 23 areformed by processing the same conductive film as the scan line 52.Meanwhile, portions parallel in the X direction in the wiring 23 have astructure in which a portion (conductive layer) obtained by processingthe same conductive film as the scan line 52 and a portion (conductivelayer) obtained by processing the same conductive film as the signalline 51 are alternately arranged. In the portions parallel in the Xdirection, the two different conductive layers overlap with each otherin regions and are electrically connected to each other through openingsin an insulating layer positioned therebetween in the regions.

In the portions of the wiring 23 which are parallel in the X direction,the portions obtained by processing the same conductive film as thesignal line intersect the scan line 52.

Structure Examples 2-1 to 2-3 are preferably used in the case where thewiring 23 and the wiring 24 have a mesh shape as illustrated in Example2 of Wiring Shape (e.g., FIGS. 7A and 7B), for example.

[Structure Example 3-1]

Although the example where the wiring 23 and the wiring 24 are formed byprocessing the same conductive films as the signal line 51 and the scanline 52 is described above, one or both of the wirings 23 and 24 may beformed by processing a conductive film different from the signal line 51and the scan line 52.

FIG. 12A illustrates an example where the wiring 23 is formed byprocessing a conductive film different from the signal line 51 unlikethe structure illustrated in FIG. 8.

Here, the wiring 23 may be positioned above the signal line 51 and thescan line 52, between the scan line 52 and the signal line 51, or belowthe signal line 51 and the scan line 52 (on the substrate 21 side). Inthat case, the wiring 23, the signal line 51, and the scan line 52 arepreferably formed over respective insulating layers.

The wiring 23 may be formed by processing the same conductive film asthe pixel electrode 36, for example. In that case, the wiring 23 can beformed through the same steps as the pixel electrode 36.

The wiring 23 and the wiring 24 are electrically connected to each otherthrough openings in the insulating layer positioned therebetween to forma mesh shape.

In the case where the wiring 23 and the signal line 51 are provided overdifferent insulating layers, they can be provided to overlap with eachother as illustrated in FIG. 12B. Thus, a space for the wiring 23 isunnecessary in the Y direction, which leads to an increase in resolutionor aperture ratio.

FIG. 12B illustrates the case where a linear portion of the signal line51 is included in the wiring 23 in a plan view; however, one embodimentof the present invention is not limited thereto. For example, the wiring23 and the signal line 51 may be provided so that the wiring 23 has asmaller width than the signal line 51 and is included in the signal line51 in a plan view. The wiring 23 and the signal line 51 may be providedso that part of the signal line 51 overlaps with the wiring 23 and theother part thereof does not overlap with the wiring 23. Thus, parasiticcapacitance between the signal line 51 and the wiring 23 can be reduced.

FIG. 13 illustrates an example where the wiring 24 is formed byprocessing a conductive film different from the scan line 52 unlike thestructure illustrated in FIG. 8.

The wiring 24 in FIG. 13 is provided in a position closer to thesubstrate 21 side than the wiring 23 and the signal line 51 are.However, one embodiment of the present invention is not limited thereto,and the wiring 24 may be provided over an insulating layer differentfrom the signal line 51, the scan line 52, the wiring 23, and the like.Furthermore, the wiring 24 may be formed by processing the sameconductive film as the pixel electrode 36.

[Structure Example 3-2]

FIG. 14A illustrates an example where the wiring 23, the wiring 24, thesignal line 51, and the scan line 52 are formed by processing respectiveconductive films. Here, the wiring 23, the wiring 24, the signal line51, and the scan line 52 may be provided over respective insulatinglayers.

In the example in FIG. 14A, the wiring 24 is positioned at least abovethe wiring 23, the signal line 51, and the scan line 52, and the wiring23 is positioned at least above the scan line 52.

FIG. 14B illustrates an example where the wiring 24 is positioned atleast below the signal line 51, and the wiring 23 is positioned at leastbelow the wiring 24 and the scan line 52.

Note that the positions of the wiring 23, the wiring 24, the signal line51, and the scan line 52 in the height direction are not limitedthereto, and a variety of stack structures can be employed.

Although not illustrated here, in each of the structures illustrated inFIGS. 14A and 14B, the wiring 23 and the signal line 51 may be providedto at least partly overlap with each other, or the wiring 24 and thescan line 52 may be provided to at least partly overlap with each other.

[Structure Example 3-3]

FIG. 15A illustrates an example where the wiring 23 having a mesh shapeis formed by processing the same conductive film as the pixel electrode36.

FIG. 15B illustrates an example where the wiring 23 having a mesh shapeis formed using a conductive film different from the signal line 51, thescan line 52, and the pixel electrode 36. In the example in FIG. 15B,the wiring 23 is positioned at least above the scan line 52 and at leastbelow the signal line 51.

Note that the position of the wiring 23 in the height direction is notlimited thereto, and the wiring 23 may be provided over an insulatinglayer different from the signal line 51, the scan line 52, and the pixelelectrode 36. The wiring 23 may be positioned below or above the signalline 51, the scan line 52, and the pixel electrode 36 or between two ofthe signal line 51, the scan line 52, and the pixel electrode 36.

Although the wiring 23 is described here, the wiring 24 (the conductivelayers 26 a and 26 b and the conductive layer 26) can have a similarstructure.

The above is the description of Structure Example 1 of Wiring.

[Structure Example of Pixel]

Specific examples of a pixel which is provided in the display portion 32and includes a liquid crystal element will be described with referenceto drawings.

[Structure Example 1 of Pixel]

FIG. 16 illustrates a structure example of the pixel circuit 80applicable to a liquid crystal element using a VA mode.

The pixel circuit 80 in FIG. 16 includes the transistor 70, a capacitor85, the pixel electrode 36, and the like. The pixel circuit 80 isconnected to a capacitor line 53 in addition to the signal line 51 andthe scan line 52.

Part of the capacitor line 53 functions as one electrode of thecapacitor 85 in the pixel circuit 80. The capacitor line 53 can besupplied with a fixed potential such as a common potential, a groundpotential, or a reference potential, for example, and may be suppliedwith a pulse potential or the like depending on a driving method.

In the example in FIG. 16, the capacitor 85 includes part of theconductive layer 74 b, part of the capacitor line 53, and an insulatinglayer (not illustrated) positioned therebetween.

In the example in FIG. 16, the capacitor line 53 is provided to extendin a direction (the Y direction) parallel to the scan line 52. Oneembodiment of the present invention is not limited thereto, and thecapacitor line 53 may be provided to extend in a direction (the Xdirection) parallel to the signal line 51 or may be provided to extendin both directions in a grid pattern.

In the example in FIG. 16, the capacitor line 53 is formed by processingthe same conductive film as the scan line 52; however, the capacitorline 53 may be formed by processing the same conductive film as thesignal line 51, the pixel electrode 36, or the like, or by processing aconductive film different from them.

In FIG. 16, the wiring 23 and the wiring 24 each have the structuredescribed in Structure Example 1-1. Specifically, the wiring 23extending in the X direction is formed by processing the same conductivefilm as the signal line 51 and the wiring 24 extending in the Ydirection is formed by processing the same conductive film as the scanline 52. Note that the structures of the wirings 23 and 24 can bereplaced with the above-described structures.

[Structure Example 2 of Pixel]

FIG. 17 illustrates a structure example of the pixel circuit 80applicable to a liquid crystal element using an FFS mode.

The pixel circuit 80 in FIG. 17 includes the transistor 70, the pixelelectrode 36, and the common electrode 38. The pixel circuit 80 isconnected to the signal line 51, the scan line 52, and a common wiring54.

The common wiring 54 is a wiring supplied with a potential supplied tothe common electrode 38. The common wiring 54 can be supplied with afixed potential such as a common potential, a ground potential, or areference potential, for example, and may be supplied with a pulsepotential or the like depending on a driving method.

In the pixel circuit 80, the common electrode 38 is provided to overlapwith the pixel electrode 36. The pixel electrode 36 has a comb-like topsurface shape. The common electrode 38 is provided to overlap with atleast a region between two adjacent projected portions of the pixelelectrode 36.

As illustrated in FIG. 17, a side of the projected portion of the pixelelectrode 36 is preferably oblique to the X direction or the Ydirection. In FIG. 17, the obliquely projected portions of the pixelelectrode 36 are arranged symmetrically with respect to the Y direction.In the pixel electrode 36, two kinds of portions projected symmetricallywith respect to the X direction or the Y direction are preferablyprovided in such a manner. The use of the pixel electrode 36 having sucha structure can expand the viewing angle of the display portion 32.

Furthermore, in the pixel circuit 80, a capacitor can be formed usingthe pixel electrode 36, the common electrode 38, and an insulating layer(not illustrated) positioned therebetween. Thus, a space for a capacitorline or a capacitor is unnecessary, which easily leads to an increase inaperture ratio or resolution.

The common electrodes 38 extend in the Y direction. Furthermore, thecommon electrodes 38 are electrically connected to the common wirings 54extending parallel to each other in the X direction. Consequently, thecommon electrodes 38 in the plurality of pixel circuits 80 adjacent inthe Y direction and the plurality of pixel circuits 80 adjacent in the Xdirection can be electrically connected to each other.

It is preferable that the width of the common electrode 38 in the Xdirection be small in a portion where the common electrode 38 and thesignal line 51 overlap with each other as illustrated in FIG. 17 becauseparasitic capacitance between the common electrode 38 and the signalline 51 can be reduced.

Although the example where the pixel electrode 36 having a comb-like topsurface shape is positioned above the common electrode 38 is describedhere, their positions can be reversed. In that case, the commonelectrode 38 has a comb-like top surface shape and the pixel electrode36 is provided to overlap with a region between two projected portionsof the common electrode 38.

In the example in FIG. 17, the common wiring 54 is formed by processingthe same conductive film as the signal line 51; however, the commonwiring 54 may be formed by processing the same conductive film as thescan line 52, the common electrode 38, the pixel electrode 36, or thelike, or by processing a conductive film different from them.

In FIG. 17, the wiring 23 and the wiring 24 each have the structuredescribed in Structure Example 1-1. Specifically, the wiring 23extending in the X direction is formed by processing the same conductivefilm as the signal line 51 and the wiring 24 extending in the Ydirection is formed by processing the same conductive film as the scanline 52. Note that the structures of the wirings 23 and 24 can bereplaced with the above-described structures.

Modification Example

Other structure examples which can be applied to the pixel circuit 80will be described below.

FIG. 18A is different from FIG. 17 mainly in the shape of the pixelelectrode 36. The pixel electrode 36 has a top surface shape includingone or more openings (slits).

In that case, as illustrated in FIG. 18A, the shape of the slit of thepixel electrode 36 is preferably a V-shape in which part of a rectangleis bent, not a rectangle. Thus, the viewing angle of the display portion32 can be expanded.

As in FIG. 17, FIG. 18A illustrates an example where the width of partof the common electrode 38 is reduced so that an area where the commonelectrode 38 and the signal line 51 intersect each other between theadjacent pixel circuits 80 is reduced. Such a structure can reduce theparasitic capacitance of the signal line 51.

FIG. 18B illustrates an example where the common electrode 38 has ashape different from that in FIG. 18A. The common electrode 38 includesan opening overlapping with the transistor 70 and a contact portionbetween the conductive layer 74 b and the pixel electrode 36. In FIG.18B, one opening is provided for each pixel circuit. The commonelectrode 38 is provided to extend in the X direction and the Ydirection. The common electrode 38 includes a region overlapping withpart of the signal line 51 and a region overlapping with part of thescan line 52. Such a structure can reduce electrical resistance of thecommon electrode 38 in the X direction and the Y direction.

FIG. 19 illustrates an example where the common electrode 38 ispositioned above the pixel electrode 36. The pixel electrode 36positioned in a lower portion also has a comb-like top surface shape.The pixel electrode 36 and the common electrode 38 are arranged toengage with each other in a plan view.

In the example in FIG. 19, a side of a projected portion of the pixelelectrode 36 and a side of a projected portion of the common electrode38 are substantially aligned with each other in a plan view. Oneembodiment of the present invention is not limited thereto, and thepixel electrode 36 and the common electrode 38 may be provided so thatthe two projected portions partly overlap with each other in a planview. Alternatively, the pixel electrode 36 and the common electrode 38may be provided so that the two projected portions are apart from eachother in a plan view.

As illustrated in FIG. 19, the signal line 51 has a top surface shapehaving a portion of which has a small width so that the width of aportion overlapping with the scan line 52, the common electrode 38, andthe like is small and the other portion of which has a large width. Withsuch a structure, the resistance of the signal line 51 itself can bereduced while parasitic capacitance between the signal line 51 andanother wiring or between the signal line 51 and another electrode isreduced. The scan line 52 also has a top surface shape having a partlysmall width so that an area overlapping with the signal line 51 issmall.

FIG. 20 illustrates an example where two pixel circuits 80 are providedin each of the X direction and the Y direction. In FIG. 20, the pixelcircuits 80 are provided symmetrically with respect to the X directionand the Y direction, and accordingly, one unit including four pixelcircuits 80 is formed.

In FIG. 20, the common electrode 38 includes a portion extending in theX direction and a portion extending in the Y direction. In FIG. 19, aportion where the common electrodes 38 included in the pixel circuits 80adjacent in the Y direction are connected to each other and a portionwhere the common electrodes 38 included in the pixel circuits 80adjacent in the X direction are connected to each other is provided foreach sub-pixel. In contrast, in FIG. 20, a portion which connects thecommon electrodes 38 included in the pixel circuits 80 adjacent in the Ydirection extends in the X direction and is provided between the twopixel circuits 80 adjacent in the Y direction. Furthermore, a portionwhich connects the common electrodes 38 included in the pixel circuits80 adjacent in the X direction extends in the Y direction and isprovided between the two pixel circuits 80 adjacent in the X direction.Thus, the area of the portions where the common electrodes 38 includedin the adjacent pixel circuits 80 are connected to each other can bereduced, so that the aperture ratio or the resolution can be increased.

The above is the description of Structure Example of Pixel.

[Structure Example 2 of Wiring]

A specific structure example of a wiring in the case where an organic ELelement is used for the display portion 32 is described below. Note thatin the following diagrams, a layer, a wiring, and the like formed byprocessing the same conductive film are shown with the same hatchingpattern for simplicity. Note that portions similar to those described inStructure Example 1 of Wiring are not described in some cases.

[Structure Example 4-1]

FIG. 21 illustrates an example of arrangement (layout) of the signalline 51, the scan line 52, a power supply line 55, the wiring 23, thewiring 24, the pixel electrode 36, and the like in the display portion32.

The signal line 51 and the wiring 23 are parallel in the X direction.The scan line 52 and the wiring 24 are parallel in the Y direction. Thesignal line 51 and the wiring 23 are formed by processing the sameconductive film, and the scan line 52 and the wiring 24 are formed byprocessing the same conductive film. Thus, the wiring 23 and the wiring24 can be formed without an increase in the number of steps.

The power supply line 55 has a function of supplying a potential or asignal to one electrode of the capacitor 85 of the pixel circuit 80. Anexample where the power supply line 55 is parallel to the signal line 51is shown here. Note that the power supply line 55 may be parallel to thescan line 52. In that case, when the power supply line 55 is formed byprocessing the same conductive film as the scan line 52, the powersupply line 55 and the signal line 51 can intersect each other and thepower supply line 55 and the wiring 23 can intersect each other withoutany special contrivance.

The pixel circuit 80 in FIG. 21 includes a transistor 70 a, a transistor70 b, the capacitor 85, and the pixel electrode 36. The pixel circuits80 are arranged in the X direction and the Y direction in a matrix. Thepixel circuit 80 corresponds to one sub-pixel included in the displayportion 32.

In the pixel circuit 80, part of the scan line 52 functions as a gateelectrode of the transistor 70 a. Part of the signal line 51 functionsas one of a source electrode and a drain electrode of the transistor 70a. As illustrated in FIG. 21, the semiconductor layer 72 is provided tooverlap with part of the scan line 52, and the signal line 51 isprovided to overlap with part of the semiconductor layer 72.Furthermore, the conductive layer 74 b functioning as the other of thesource electrode and the drain electrode of the transistor 70 a isprovided on a side opposite to the signal line 51 of the semiconductorlayer 72. The conductive layer 74 b is electrically connected to theconductive layer 76. A portion of the conductive layer 76 functions as agate electrode of the transistor 70 b. The conductive layer 76 and thepower supply line 55 are provided to overlap with each other so that thecapacitor 85 is formed. In other words, another portion of theconductive layer 76 functions as one electrode of the capacitor 85. Aportion of the power supply line 55 functions as the other electrode ofthe capacitor 85 and another portion of the power supply line 55functions as one of a source and a drain of the transistor 70 b. Theother of the source and the drain of the transistor 70 b is electricallyconnected to the pixel electrode 36.

[Structure Example 4-2]

FIG. 22A illustrates an example where the structure of the wiring 24 isdifferent from that in FIG. 21. The wiring 24 in FIG. 22A has astructure in which a portion formed by processing the same conductivefilm as the signal line 51 and a portion formed by processing the sameconductive film as the scan line 52 are alternately arranged as inStructure Example 1-2. The two types of portions overlap with each otherin regions and are electrically connected to each other through openingsin an insulating layer positioned therebetween in the regions.

Each of the portions of the wiring 24 that are formed by processing thesame conductive film as the scan line 52 intersects at least one of thesignal line 51, the power supply line 55, and the wiring 23.

[Structure Example 4-3]

FIG. 22B illustrates an example where the structure of the wiring 23 isdifferent from that in FIG. 21. The wiring 23 in FIG. 22B has astructure in which a portion formed by processing the same conductivefilm as the signal line 51 and a portion formed by processing the sameconductive film as the scan line 52 are alternately arranged as inStructure Example 1-3. The two types of portions overlap with each otherin regions and are electrically connected to each other through openingsin an insulating layer positioned therebetween in the regions.

[Structure Example 5-1]

FIG. 23 illustrates an example where the wiring 23 includes both ofportions parallel in the X direction and portions parallel in the Ydirection as in Structure Example 2-1. Although the wiring 23 is usedfor the description here, the wiring 24, the conductive layer 26, theconductive layer 26 a, the conductive layer 26 b, and the like can havesimilar shapes.

[Structure Example 5-2]

FIG. 24A illustrates an example where the structure of the wiring 23 isdifferent from that in FIG. 23. In the structure in FIG. 24A, portionsparallel in the X direction in the wiring 23 are formed by processingthe same conductive film as the signal line 51 as in Structure Example2-2. Meanwhile, portions parallel in the Y direction in the wiring 23have a structure in which a portion (conductive layer) obtained byprocessing the same conductive film as the signal line 51 and a portion(conductive layer) obtained by processing the same conductive film asthe scan line 52 are alternately arranged. In the portions parallel inthe Y direction, the two types of different conductive layers overlapwith each other in regions and are electrically connected to each otherthrough openings in an insulating layer positioned therebetween in theregions.

In the portions of the wiring 23 which are parallel in the Y direction,the portions obtained by processing the same conductive film as the scanline 52 intersect at least one of the signal line 51 and the powersupply line 55.

[Structure Example 5-3]

FIG. 24B illustrates an example where the structure of the wiring 23 isdifferent from those in FIG. 23 and FIG. 24A. In the structure in FIG.24B, portions parallel in the Y direction in the wiring 23 are formed byprocessing the same conductive film as the scan line 52 as in StructureExample 2-3. Meanwhile, portions parallel in the X direction in thewiring 23 have a structure in which a portion (conductive layer)obtained by processing the same conductive film as the scan line 52 anda portion (conductive layer) obtained by processing the same conductivefilm as the signal line 51 are alternately arranged. In the portionsparallel in the X direction, the two different conductive layers overlapwith each other in regions and are electrically connected to each otherthrough openings in an insulating layer positioned therebetween in theregions.

[Structure Example 6-1]

Although the example where the wiring 23 and the wiring 24 are formed byprocessing the same conductive films as the signal line 51 and the scanline 52 is described above, one or both of the wirings 23 and 24 may beformed by processing a conductive film different from the signal line 51and the scan line 52 as in Structure Example 3-1 or the like.

FIG. 25A and FIG. 25B each illustrate an example where the wiring 23 isformed by processing a conductive film different from the signal line 51unlike the structure illustrated in FIG. 21.

FIG. 26 illustrates an example where the wiring 24 is formed byprocessing a conductive film different from the scan line 52 unlike thestructure illustrated in FIG. 21.

[Structure Example 6-2]

FIG. 27A illustrates an example where the wiring 23, the wiring 24, thesignal line 51, and the scan line 52 are formed by processing respectiveconductive films as in Structure Example 3-2. Here, the wiring 23, thewiring 24, the signal line 51, and the scan line 52 may be provided overrespective insulating layers.

In the example in FIG. 27A, the wiring 24 is positioned at least abovethe wiring 23, the signal line 51, and the scan line 52, and the wiring23 is positioned at least above the scan line 52.

FIG. 27B illustrates an example where the wiring 24 is positioned atleast below the signal line 51, and the wiring 23 is positioned at leastbelow the wiring 24 and the scan line 52.

[Structure Example 6-3]

FIG. 28A illustrates an example where the wiring 23 having a mesh shapeis formed by processing the same conductive film as the pixel electrode36 as in Structure Example 3-3.

FIG. 28B illustrates an example where the wiring 23 having a mesh shapeis formed using a conductive film different from the signal line 51, thescan line 52, and the pixel electrode 36. In the example in FIG. 28B,the wiring 23 is positioned at least above the scan line 52 and at leastbelow the signal line 51.

The above is the description of Structure Example 2 of Wiring.

[Configuration Example of Circuit]

FIG. 29 illustrates an example of a circuit diagram of a touch panel ofone embodiment of the present invention. In FIG. 29, part of a displayportion in which two kinds of wirings included in a touch sensor areeach provided in a stripe form is illustrated. The example in FIG. 29corresponds to the examples in FIGS. 6A and 6B and the like.

Pixels 90 arranged in a matrix each include the transistor 70 and acircuit 91. The circuit 91 includes at least one display element. Avariety of display elements can be applied to the display element.Typically, the above-described liquid crystal element 60 or thelight-emitting element 40 is preferably used.

A wiring 23 a and a wiring 23 b each include a plurality of portionsextending in a direction parallel to the signal line 51 (the Xdirection). Furthermore, a wiring 24 a and a wiring 24 b include aplurality of portions extending in a direction parallel to the scan line52 (the Y direction). The wiring 23 a, the wiring 23 b, the wiring 24 a,and the wiring 24 b have the plurality of portions electricallyconnected to each other in a region outside the display portion. Notethat in the following description, the wiring 23 a and the wiring 23 bare collectively referred to as the wiring 23 and the wiring 24 a andthe wiring 24 b are collectively referred to as the wiring 24 in somecases.

As illustrated in FIG. 29, the wiring 23 and the wiring 24 formcapacitors. In other words, the capacitors are arranged in a matrix toform a touch sensor. The touch sensor can sense an object by utilizing achange in capacitance of the capacitor due to the approach of theobject. The capacitance includes, for example, a first capacitancecomponent of a portion where the wiring 23 and the wiring 24 overlapwith each other and a second capacitance component formed when thewiring 23 and the wiring 24 are provided close to each other. The secondcapacitance component is mainly changed owing to the approach of theobject.

An example where four wirings (the wiring 23 a, the wiring 23 b, thewiring 24 a, and the wiring 24 b) are provided is shown here forsimplicity. The wirings extending in the X direction (the wiring 23 aand the wiring 23 b) each have two portions parallel in the X directionand the wirings extending in the Y direction (the wiring 24 a and thewiring 24 b) each have two portions parallel in the Y direction;however, one embodiment of the present invention is not limited thereto,and three or more portions parallel in the X direction or three or moreportions parallel in the Y direction may be provided. The number ofpixels 90 provided between two linear portions of one wiring is notlimited to the example in FIG. 29 as long as at least one pixel 90 isprovided.

In FIG. 30, part of a display portion in which two kinds of wiringsincluded in a touch sensor are each have a mesh shape is illustrated.The example in FIG. 30 corresponds to the examples in FIGS. 7A and 7Band the like. FIG. 30 illustrates an intersection of the wiring 23 andthe wiring 24 which each have a mesh shape.

Also in the example in FIG. 30, the wiring 23 and the wiring 24 formcapacitors. Detection can be performed by utilizing a change incapacitance of the capacitor.

The above is the description of Configuration Example of Circuit.

[Cross-Sectional Structure Example 3]

A specific cross-sectional structure example of a touch panel module ofone embodiment of the present invention in which a liquid crystalelement is applied to a display element is described below.

[Cross-Sectional Structure Example 3-1]

FIG. 31 is a schematic cross-sectional view of the touch panel module10. FIG. 31 illustrates an example of cross sections of a regionincluding the FPC 42, a region including the circuit 34, a regionincluding the display portion 32, and the like in FIG. 1A.

The substrate 21 and the substrate 31 are attached to each other with anadhesive layer 141. A region surrounded by the substrate 21, thesubstrate 31, and the adhesive layer 141 is filled with a liquid crystal112. A polarizing plate 130 a is provided on an outer surface of thesubstrate 31. A polarizing plate 130 b is provided on an outer surfaceof the substrate 21.

Although not illustrated, a backlight can be provided outside thepolarizing plate 130 a or the polarizing plate 130 b.

A touch sensor 22 including the wiring 23 and the wiring 24, a pixelelectrode 111 of the liquid crystal element 60, a transistor 201, atransistor 202, a capacitor 203, a connection portion 204, the wiring35, and the like are provided over the substrate 21. For example, thetransistor 201 corresponds to the transistor 70 described above.

A coloring layer 131, a light-blocking layer 132, an insulating layer123, a common electrode 113 of the liquid crystal element 60, a spacer124, and the like are provided over the substrate 31.

Insulating layers such as an insulating layer 211, an insulating layer212, an insulating layer 213, and an insulating layer 214 are providedover the substrate 21. A portion of the insulating layer 211 functionsas a gate insulating layer of each transistor, and another portionthereof functions as a dielectric of the capacitor 203. The insulatinglayer 212, the insulating layer 213, and the insulating layer 214 areprovided to cover each transistor, the capacitor 203, and the like. Theinsulating layer 214 functions as a planarization layer. Note that anexample where the three insulating layers, the insulating layers 212,213, and 214, are provided to cover the transistors and the like isdescribed here; however, one embodiment of the present invention is notlimited to this example, and four or more insulating layers, a singleinsulating layer, or two insulating layers may be provided. Theinsulating layer 214 functioning as a planarization layer is notnecessarily provided when not needed.

The transistor 201 and the transistor 202 each include a conductivelayer 221 part of which functions as a gate, conductive layers 222 partof which functions as a source electrode and a drain electrode, and asemiconductor layer 231. Here, a plurality of layers obtained byprocessing the same conductive film are shown with the same hatchingpattern.

In the transistor 202, one of the pair of conductive layers 222 which isnot electrically connected to the pixel electrode 111 functions as partof a signal line. The conductive layer 221 functioning as a gateelectrode of the transistor 202 also functions as part of a scan line.

FIG. 31 illustrates an example where the wiring 23 is formed byprocessing the same conductive film as the conductive layer 222 and thewiring 24 is formed by processing the same conductive film as theconductive layer 221.

FIG. 31 illustrates a cross section of one sub-pixel as an example ofthe display portion 32. The sub-pixel includes, for example, thetransistor 202, the capacitor 203, the liquid crystal element 60, andthe coloring layer 131. For example, the coloring layers 131 areselectively formed so that a sub-pixel exhibiting a red color, asub-pixel exhibiting a green color, and a sub-pixel exhibiting a bluecolor are arranged; thus, full-color display can be achieved. Here, thepixel circuit (sub-pixel circuit) includes the transistor 202, thecapacitor 203, the pixel electrode 111, a wiring, and the like.

FIG. 31 illustrates an example of the circuit 34 in which the transistor201 is provided.

Although the transistors 201 and 202 each include one gate electrode inFIG. 31, the semiconductor layer 231 where a channel is formed may beprovided between two gate electrodes. Such a structure enables controlof threshold voltages of transistors. In that case, the two gateelectrodes may be connected to each other and supplied with the samesignal to operate the transistors. Such transistors can have higherfield-effect mobility and thus have higher on-state current than othertransistors. Consequently, a circuit capable of high-speed operation canbe obtained. Furthermore, the area occupied by a circuit portion can bereduced. The use of the transistor having high on-state current canreduce signal delay in wirings and can reduce display unevenness even ina display panel or a touch panel in which the number of wirings isincreased because of increase in size or resolution.

Note that the transistor included in the circuit 34 and the transistorincluded in the display portion 32 may have the same structure. Aplurality of transistors included in the circuit 34 may have the samestructure or different structures. A plurality of transistors includedin the display portion 32 may have the same structure or differentstructures.

A material through which impurities such as water or hydrogen do noteasily diffuse is preferably used for at least one of the insulatinglayers 212 and 213 which cover the transistors. That is, the insulatinglayer 212 or the insulating layer 213 can function as a barrier film.Such a structure can effectively suppress diffusion of the impuritiesinto the transistors from the outside, and a highly reliable touch panelcan be provided.

The pixel electrode 111 is provided over the insulating layer 214. Thepixel electrode 111 is electrically connected to one of a source and adrain of the transistor 202 through an opening formed in the insulatinglayer 214, the insulating layer 213, the insulating layer 212, and thelike. The pixel electrode 111 is also electrically connected to oneelectrode of the capacitor 203.

The insulating layer 123 is provided on the substrate 31 side to coverthe coloring layer 131 and the light-blocking layer 132. The insulatinglayer 123 may have a function of a planarization film. The insulatinglayer 123 enables the common electrode 113 to have an almost flatsurface, resulting in a uniform alignment state of the liquid crystal112.

In FIG. 31, the liquid crystal element 60 includes the pixel electrode111, part of the common electrode 113, and the liquid crystal 112sandwiched therebetween.

Alignment films for controlling alignment of the liquid crystal 112 maybe provided on surfaces of the pixel electrode 111, the common electrode113, the insulating layer 214, and the like which are in contact withthe liquid crystal 112.

In the structure of FIG. 31, the wirings 23 and 24 are provided not tooverlap with the liquid crystal element 60. Furthermore, it ispreferable that the wirings 23 and 24 be provided to overlap with thelight-blocking layer 132.

In the liquid crystal element 60, the pixel electrode 111 and the commonelectrode 113 each have a function of transmitting visible light. Byhaving such a structure, the liquid crystal element 60 can be atransmissive liquid crystal element. For example, in the case where abacklight is provided on the substrate 31 side, light from the backlightwhich is polarized by the polarizing plate 130 a passes through thesubstrate 31, the common electrode 113, the liquid crystal 112, thepixel electrode 111, and the substrate 21, and then reaches thepolarizing plate 130 b. In this case, alignment of the liquid crystal112 is controlled with a voltage that is applied between the pixelelectrode 111 and the common electrode 113, and thus optical modulationof light can be controlled. That is, the intensity of light emittedthrough the polarizing plate 130 b can be controlled. Light other thanone in a particular wavelength region of the incident light is absorbedby the coloring layer 131, and thus, emitted light is red light, forexample.

As the polarizing plate 130 b, a linear polarizing plate or a circularlypolarizing plate can be used. An example of a circularly polarizingplate is a stack including a linear polarizing plate and a quarter-waveretardation plate. In particular, as illustrated in FIG. 31, in the casewhere the wiring 23 and the wiring 24 included in the touch sensor areprovided in a position closer to the substrate 21 side than thelight-blocking layer 132 is, external light is reflected by the wiringsand the reflected light is visually recognized in some cases. In thiscase, reflection can be suppressed with a circularly polarizing plateused as the polarizing plate 130 b.

In the case where a circularly polarizing plate is used as thepolarizing plate 130 b, a circularly polarizing plate may be also usedas the polarizing plate 130 a and a general linear polarizing plate maybe used. The cell gap, alignment, driving voltage, and the like of theliquid crystal element used as the liquid crystal element 60 arecontrolled depending on the kinds of polarizing plates used as thepolarizing plates 130 a and 130 b so that desirable contrast isobtained.

The liquid crystal element 60 can use a variety of modes given inCross-sectional Structure Example 1.

The common electrode 113 is electrically connected to a conductive layerprovided on the substrate 21 through a connector 243 in a portion closeto an end portion of the substrate 31. Thus, a potential or a signal canbe supplied from an FPC or an IC provided on the substrate 21 side tothe common electrode 113.

As the connector 243, a conductive particle can be used, for example. Asthe conductive particle, a particle of an organic resin, silica, or thelike coated with a metal material can be used. It is preferable to usenickel or gold as the metal material because contact resistance can bedecreased. It is also preferable to use a particle coated with layers oftwo or more kinds of metal materials, such as a particle coated withnickel and further with gold. As the connector 243, a material capableof elastic deformation or plastic deformation is preferably used. Asillustrated in FIG. 31, the conductive particle has a shape that isvertically crushed in some cases. With the crushed shape, the contactarea between the connector 243 and a conductive layer electricallyconnected to the connector 243 can be increased, thereby reducingcontact resistance and suppressing the generation of problems such asdisconnection.

The connector 243 is preferably provided so as to be covered with theadhesive layer 141. For example, a paste or the like for forming theadhesive layer 141 may be applied, and then, the connector 243 may beprovided. A structure in which the connector 243 is provided in aportion provided with the adhesive layer 141 can be applied to, forexample, a structure in which the adhesive layer 141 is provided in theperipheral region, e.g., a display device with a solid sealing structureor a display device with a hollow sealing structure.

The connection portion 204 is provided in a region near an end portionof the substrate 21. The connection portion 204 is electricallyconnected to the FPC 42 through a connection layer 242. In the structurein FIG. 31, the connection portion 204 is formed by stacking part of thewiring 35 and a conductive layer obtained by processing the sameconductive film as the pixel electrode 111.

The above is the description of Cross-sectional Structure Example 3-1.

[Cross-Sectional Structure Example 3-2]

A cross-sectional structure example of the touch panel module 10 thatincludes a liquid crystal element having a mode different from that inCross-sectional Structure Example 3-1 is described below. Note thatdescriptions of the portions already described are omitted and differentportions are described below.

FIG. 32 illustrates an example where the liquid crystal element 60 is aliquid crystal element using an FFS mode. The liquid crystal element 60includes a pixel electrode 151, a liquid crystal 152, and a commonelectrode 153.

The common electrode 153 is provided over the insulating layer 214. Theinsulating layer 215 is provided to cover the common electrode 153, andthe pixel electrode 151 is provided over the insulating layer 215. Thepixel electrode 151 is electrically connected to one of a source and adrain of the transistor 202 through an opening provided in theinsulating layers 212 to 215.

The pixel electrode 151 has a comb-like top surface shape or a topsurface shape with a slit. The common electrode 153 is provided tooverlap with the pixel electrode 151. There is a portion where the pixelelectrode 151 is not provided over the common electrode 153 in a regionoverlapping with the coloring layer 131 and the like.

FIG. 32 illustrates an example where the pixel electrode 151 having acomb-like top surface shape or a top surface shape with a slit isprovided above the insulating layer 215 and the common electrode 153 isprovided below the insulating layer 215. As illustrated in FIG. 33, thecommon electrode 153 may be formed above the insulating layer 215 andthe pixel electrode 151 may be formed below the insulating layer 215. Inthat case, the pixel electrode 151 below the insulating layer 215 may beelectrically connected to one of a source and a drain of the transistor202. The common electrode 153 above the insulating layer 215 may have acomb-like top surface shape or a top surface shape with a slit.

In FIG. 32, the pixel electrode 151 and the common electrode 153 arestacked with the insulating layer 215 positioned therebetween to formthe capacitor 203. Therefore, another capacitor is not necessarilyprovided, and thus the aperture ratio of the pixel can be increased.

With the use of a conductive material that transmits visible light forthe common electrode 153, a transmissive liquid crystal element can beobtained. When both of the pixel electrode 151 and the common electrode153 are formed using a conductive material that transmits visible light,the aperture ratio can be further increased, which is preferable.

In the case where the liquid crystal element 60 is a reflective liquidcrystal element, one or both of the pixel electrode 151 and the commonelectrode 153 may be formed using a material that reflects visiblelight. When both of them are formed using a material that reflectsvisible light, the aperture ratio can be increased. The common electrode153 may be formed using a material that reflects visible light and thepixel electrode 151 may be formed using a material that transmitsvisible light.

Alternatively, the pixel electrode 151 may be formed using a materialthat reflects visible light and the common electrode 153 may be formedusing a material that transmits visible light to form asemi-transmissive liquid crystal element. In that case, a reflectivemode in which light reflected by the pixel electrode 151 is used and atransmissive mode in which light from a backlight which passes through aslit in the pixel electrode 151 can be switched.

Alternatively, in the case of employing a horizontal electric fieldmode, a liquid crystal exhibiting a blue phase for which an alignmentfilm is unnecessary may be used. A blue phase is one of liquid crystalphases, which is generated just before a cholesteric phase changes intoan isotropic phase while the temperature of cholesteric liquid crystalis increased. Since the blue phase appears only in a narrow temperaturerange, a liquid crystal composition in which several weight percent ormore of a chiral material is mixed is used for the liquid crystal layerin order to improve the temperature range. The liquid crystalcomposition which includes liquid crystal exhibiting a blue phase and achiral material has a short response time and optical isotropy. Inaddition, the liquid crystal composition which includes liquid crystalexhibiting a blue phase and a chiral material does not need alignmenttreatment and has a small viewing angle dependence. An alignment filmdoes not need to be provided and rubbing treatment is thus notnecessary; accordingly, electrostatic discharge damage caused by therubbing treatment can be prevented and defects and damage of the liquidcrystal display device in the manufacturing process can be reduced.

[Cross-Sectional Structure Example 3-3]

A cross-sectional structure example of the touch panel module 10including a liquid crystal element having a mode different from those inCross-sectional Structure Examples 3-1 and 3-2 is described below. Notethat descriptions of the portions already described are omitted anddifferent portions are described below.

FIG. 34 illustrates an example where the liquid crystal element 60 is aliquid crystal element using an IPS mode. The liquid crystal element 60includes the pixel electrode 151, the liquid crystal 152, and the commonelectrode 153.

The pixel electrode 151 and the common electrode 153 are provided overthe insulating layer 214. The pixel electrode 151 and the commonelectrode 153 each have a comb-like top surface shape and are providedto engage with each other. The pixel electrode 151 and the commonelectrode 153 are preferably formed by processing the same conductivefilm. In FIG. 34, the pixel electrode 151 and the common electrode 153are shown with different hatching patterns for clarity.

The above is the description of Cross-sectional Structure Example 3.

[Cross-Sectional Structure Example 4]

A specific cross-sectional structure example of a touch panel module ofone embodiment of the present invention in which an organic EL elementis applied to a display element is described below. Note that portionssimilar to those described above are not described in some cases.

[Cross-Sectional Structure Example 4-1]

FIG. 35 is a schematic cross-sectional view of the touch panel module10. FIG. 35 illustrates an example of cross sections of a regionincluding the FPC 42, a region including the circuit 34, a regionincluding the display portion 32, and the like in FIG. 1A. The displayportion 32 in FIG. 35 illustrates an example of a cross section takenalong line X1-X2 in FIG. 21.

The substrate 21 and the substrate 31 are attached to each other withthe adhesive layer 141. Part of the adhesive layer 141 has a function ofsealing the light-emitting element 40. The polarizing plate 130 ispreferably provided on an outer surface of the substrate 21.

The touch sensor 22 including the wiring 23 and the wiring 24, thelight-emitting element 40, the transistor 201, the transistor 202, atransistor 205, the capacitor 203, the connection portion 204, thecoloring layer 131, the wiring 35, and the like are provided over thesubstrate 21. The light-emitting element 40 has a stacked structure ofthe pixel electrode 111, an EL layer 102, and a common electrode 103.The light-emitting element 40 is a bottom-emission light-emittingelement in which light is emitted to the substrate 21 side.

Insulating layers such as the insulating layer 211, the insulating layer212, the insulating layer 213, the insulating layer 214, and theinsulating layer 215 are provided over the substrate 21. A portion ofthe insulating layer 211 functions as a gate insulating layer of eachtransistor, and another portion thereof functions as a dielectric of thecapacitor 203. The insulating layer 212, the insulating layer 213, andthe insulating layer 214 are provided to cover each transistor, thecapacitor 203, and the like. The insulating layer 214 functions as aplanarization layer. Note that an example where the three insulatinglayers, the insulating layers 212, 213, and 214, are provided to coverthe transistors and the like is described here; however, one embodimentof the present invention is not limited to this example, and four ormore insulating layers, a single insulating layer, or two insulatinglayers may be provided. The insulating layer 214 functioning as aplanarization layer is not necessarily provided when not needed. Theinsulating layer 215 is provided to cover an end portion of the pixelelectrode 111, a contact portion which electrically connects the pixelelectrode 111 and the transistor 205, and the like. The insulating layer215 functions as a planarization layer.

The transistor 201, the transistor 202, and the transistor 205 eachinclude the conductive layer 221 part of which functions as a gate, theconductive layer 222 part of which functions as a source electrode and adrain electrode, and the semiconductor layer 231. Here, a plurality oflayers obtained by processing the same conductive film are shown withthe same hatching pattern.

In the example in FIG. 35, the capacitor 203 includes part of theconductive layer 221 functioning as a gate electrode of the transistor205, part of the insulating layer 211, and part of the conductive layer222 functioning as a source electrode and a drain electrode of thetransistor 205.

In the transistor 202, one of the pair of conductive layers 222 which isnot electrically connected to the capacitor 203 functions as part of asignal line. The conductive layer 221 functioning as a gate electrode ofthe transistor 202 also functions as part of a scan line.

FIG. 35 illustrates an example where the wiring 23 is formed byprocessing the same conductive film as the conductive layer 222 and thewiring 24 is formed by processing the same conductive film as theconductive layer 221.

FIG. 35 illustrates a cross section of one sub-pixel as an example ofthe display portion 32. The sub-pixel includes, for example, thetransistor 202, the capacitor 203, the transistor 205, thelight-emitting element 40, and the coloring layer 131. For example, thecoloring layers 131 are selectively formed so that a sub-pixelexhibiting a red color, a sub-pixel exhibiting a green color, and asub-pixel exhibiting a blue color are arranged; thus, full-color displaycan be achieved. Here, the pixel circuit (sub-pixel circuit) includesthe transistor 202, the capacitor 203, the transistor 205, the pixelelectrode 111, a wiring, and the like.

Although the transistors 201, 202, and 205 each include one gateelectrode in FIG. 35, the semiconductor layer 231 where a channel isformed may be provided between two gate electrodes.

The pixel electrode 111 is provided over the insulating layer 214. Thepixel electrode 111 is electrically connected to one of a source and adrain of the transistor 205 through an opening formed in the insulatinglayer 214, the insulating layer 213, the insulating layer 212, and thelike. The other of the source and the drain of the transistor 205 iselectrically connected to the capacitor 203.

The coloring layer 131 is provided over the insulating layer 213. Thecoloring layer 131 is provided to overlap with the light-emittingelement 40. The insulating layer 214 functioning as a planarizationlayer is provided to cover the coloring layer 131. The coloring layer131 is preferably covered with the insulating layer 214 because asurface of the pixel electrode 111 can be almost flat.

In the light-emitting element 40, the pixel electrode 111 has a functionof transmitting visible light and the common electrode 103 has afunction of reflecting visible light. With such a structure, abottom-emission light-emitting element in which light is emitted to thesubstrate 21 side which supports the light-emitting element 40 can beprovided. Note that both of the pixel electrode 111 and the commonelectrode 103 have a function of transmitting visible light to obtain adual-emission light-emitting element.

In FIG. 35, a light-emitting element exhibiting a white color can bepreferably used as the light-emitting element 40. Thus, thelight-emitting elements 40 do not need to be separately fabricated inrespective sub-pixels; accordingly, an extremely high definition touchpanel can be provided. In that case, when light from the light-emittingelement 40 passes through the coloring layer 131, light out of aspecific wavelength range is absorbed by the coloring layer 131.Consequently, red light is extracted, for example.

As the polarizing plate 130, a circularly polarizing plate is preferablyused. In the case where the substrate 21 side functions as the displaysurface side as illustrated in FIG. 35, particularly, the wiring 23 andthe wiring 24 included in the touch sensor reflect external light andthe reflected light is visually recognized in some cases. In this case,reflection can be suppressed with a circularly polarizing plate used asthe polarizing plate 130.

FIG. 36 illustrates a cross-sectional structure example of the touchpanel module 10 with a hollow sealing structure.

In the example in FIG. 36, the adhesive layer 141 does not cover thelight-emitting element 40 and is provided in a peripheral portion of thesubstrate 31. There is a space 142 between the common electrode 103 andthe substrate 31.

The space 142 may be filled with air, preferably an inert gas such as arare gas or a nitrogen gas. When the space 142 in a steady state isunder reduced pressure relative to the atmospheric pressure, thefollowing phenomenon can be prevented: the space 142 expands dependingon the usage environment (e.g., pressure or temperature) and thus thesubstrate 31 or the substrate 21 expands. Meanwhile, when the space 142is under positive pressure relative to the atmospheric pressure,impurities such as moisture can be prevented from being diffused fromthe substrate 31, the substrate 21, the adhesive layer 141, or a gaptherebetween into the space 142.

In the example in FIG. 36, a dry agent 143 is provided between thesubstrate 31 and the common electrode 103. In that case, when thethickness of at least a portion of the substrate 31 which overlaps withthe display portion 32 is smaller than that of a peripheral portion, thedry agent 143 can be provided without an increase in thickness of thetouch panel module 10.

As the drying agent 143, for example, a substance which adsorbs moistureby chemical adsorption, such as an oxide of an alkaline earth metal(e.g., a calcium oxide or a barium oxide), can be used. Alternatively, asubstance that adsorbs moisture by physical adsorption, such as zeoliteor silica gel, may be used.

The above is the description of Cross-sectional Structure Example 4-1.

[Cross-Sectional Structure Example 4-2]

FIG. 37 illustrates an example where the coloring layer 131 is formedover a different substrate.

In FIG. 37, the coloring layer 131 and the light-blocking layer 132 areformed over a substrate 161. The substrate 161 is attached to thesubstrate 21 with an adhesive layer 251.

The coloring layer 131 is provided to overlap with at least thelight-emitting element 40. The light-blocking layer 132 is provided tooverlap with the wiring 23, the wiring 24, the transistor 202, thetransistor 205, the capacitor 203, the transistor 201, and the like.

The light-blocking layer 132 has a function of blocking visible light.

Such a structure can suppress reflection of external light by the wiring23, the wiring 24, or the like and improve contrast even when thesubstrate 21 side functions as the display surface side.

In that case, the substrate 161 can also be used as a protectivesubstrate for protecting the substrate 21 and the like. In that case, aprotective layer (such as a ceramic coat) is preferably provided overthe substrate. The protective layer can be formed using an inorganicinsulating material such as silicon oxide, aluminum oxide, yttriumoxide, or yttria-stabilized zirconia (YSZ). Alternatively, temperedglass may be used for the substrate. The tempered glass which can beused here is one that has been subjected to physical or chemicaltreatment by an ion exchange method, a thermal tempering method, or thelike and has a surface to which compressive stress has been added.

FIG. 38 illustrates an example where the coloring layer 131 and thelight-blocking layer 132 are formed on a surface of the substrate 21opposite to a surface over which the wiring 23 and the like are formed.

In this case, a substrate 162 may be provided with the adhesive layer251 to protect the coloring layer 131 and the light-blocking layer 132.

[Cross-Sectional Structure Example 4-3]

FIG. 39 illustrates an example of a cross-sectional structure in whichthe light-emitting elements 40 are fabricated in respective sub-pixels.

Whereas the EL layers 102 in FIG. 35 and the like are uniformlyprovided, the EL layer 102 in FIG. 39 has an island-shaped top surface.

Since the EL layers 102 can be formed in respective sub-pixels in theexample in FIG. 39, the light-emitting element 40 in one sub-pixel canexhibit a color different from that exhibited by a light-emittingelement in an adjacent sub-pixel. Consequently, full-color display canbe performed without the coloring layer 131.

[Cross-Sectional Structure Example 4-4]

FIG. 40 illustrates an example of a top-emission light-emitting element.

The light-emitting element 40 in FIG. 40 emits light to the substrate 31side. Therefore, the substrate 31 side functions both as the displaysurface side and as the touch surface side. The polarizing plate 130 ispositioned on an outer surface of the substrate 31.

The pixel electrode 111 of the light-emitting element 40 has a functionof reflecting visible light. The common electrode 103 has a function ofblocking visible light.

The substrate 31 is provided with the coloring layer 131, thelight-blocking layer 132, and the like.

In the example in FIG. 40, the spacer 124 is provided on the substrate31 side. The spacer 124 has a function of adjusting the distance betweenthe substrate 21 and the substrate 31. There is a gap between the spacer124 and the common electrode 103 or the insulating layer 215 in FIG. 40;however, the spacer 124 may be in contact with the common electrode 103or the insulating layer 215. Although the spacer 124 is provided on thesubstrate 31 side in the structure described here, the spacer 124 may beprovided on the substrate 21 side (e.g., over the insulating layer 215).Alternatively, a particulate spacer may be used instead of the spacer124. Although a material such as silica can be used for the particulatespacer, an elastic material such as an organic resin or rubber ispreferably used. In some cases, the particulate spacer may be verticallycrushed.

In the case where the light-emitting element 40 has a top-emissionstructure as illustrated in FIG. 40, the pixel electrode 111 can beprovided to cover the transistor 202, the transistor 205, the capacitor203, and the like. Thus, the aperture ratio of the pixel can bepreferably increased.

In the example in FIG. 40, the common electrode 103 includes an opening.The opening is provided to overlap with the wiring 23 and the wiring 24.In this manner, even in the case where the substrate 31 side functionsas the touch surface, a region where a conductive layer which could besupplied with a predetermined potential is not positioned is preferablyprovided between the touch surface and the wiring 23 or the wiring 24.Thus, a change in capacitance between the wiring 23 and the wiring 24can be increased by operation such as touch because an electric fieldfrom the wiring 23 or the wiring 24 is not blocked by the conductivelayer, and accordingly, detection sensitivity can be increased.

In that case, a region where the EL layer 102 is not provided ispreferably provided in a position overlapping with the wiring 23 and thewiring 24. In addition, when the EL layer 102 is provided so that an endportion of the EL layer 102 is also covered with the common electrode103, the EL layer 102 is not exposed, so that high reliability can beachieved.

Furthermore, in the case where the light-blocking layer 132 including aplurality of openings is uniformly provided across the display portion32, the light-blocking layer 132 preferably has an insulating property.When the light-blocking layer 132 overlapping with the wiring 23 or thewiring 24 has an insulating property, an electric field from the wiring23 or the wiring 24 is prevented from being blocked by thelight-blocking layer 132, so that detection sensitivity can beincreased.

Modification Example

FIG. 41 illustrates a cross-sectional structure example of the touchpanel module 10 in which a substrate 171 and a substrate 172 which haveflexibility are used as a pair of substrates. Part of a display surfaceof the touch panel module 10 in FIG. 41 is bendable.

In FIG. 41, the substrate 171, the adhesive layer 251, and an insulatinglayer 216 are provided instead of the substrate 21. Furthermore, thesubstrate 172 is provided instead of the substrate 31.

The conductive layer 221 and the insulating layer 211 are provided onone surface of the insulating layer 216. The substrate 171 is attachedto the opposite surface of the insulating layer 216 with the adhesivelayer 251.

The substrate 171 and the substrate 172 can each be formed using aflexible material. Note that the substrate 171 and the substrate 172 mayeach have a function of a protective layer for protecting a surface ofthe touch panel module 10. The substrate 171 and the substrate 172 donot necessarily have a function of supporting the transistors, thelight-emitting element, a wiring, or the like.

The insulating layer 216 preferably has a function of suppressingdiffusion of impurities such as water or hydrogen.

In the example in FIG. 41, the insulating layer 217 is provided to coverthe common electrode 103. The insulating layer 217 has a function ofsuppressing diffusion of impurities such as water into the commonelectrode 103, the EL layer 102, or the like.

It is particularly preferable that the common electrode 103 be providedto cover an end portion of the EL layer 102 and the insulating layer 217be provided to cover an end portion of the common electrode 103 asillustrated in FIG. 41. Thus, diffusion of impurities into the commonelectrode 103 or the EL layer 102 can be more effectively suppressed.

The touch panel module 10 in FIG. 41 has a structure in which eachtransistor and the light-emitting element 40 are sandwiched between theinsulating layer 216 and the insulating layer 217. Thus, even in thecase where the substrate 171, the substrate 172, the adhesive layer 251,the adhesive layer 141, or the like is formed using a material throughwhich impurities such as water or hydrogen are easily diffused, theinsulating layer 216 and the insulating layer 217 positioned furtherinward (closer to each transistor or the light-emitting element 40) thanthese components can suppress impurity diffusion, so that reliabilitycan be increased.

FIG. 42 illustrates an example where a top-emission light-emittingelement is used as the light-emitting element 40. In FIG. 42, aninsulating layer 218, an adhesive layer 252, and the substrate 172 areprovided instead of the substrate 31 in FIG. 40. The substrate 171, theadhesive layer 251, and the insulating layer 216 are provided instead ofthe substrate 21.

The coloring layer 131, the light-blocking layer 132, the spacer 124,and the like are provided on one surface of the insulating layer 218.The substrate 172 is attached to the opposite surface of the insulatinglayer 218 with the adhesive layer 252.

A material through which impurities such as water do not easily diffuseis preferably used for the insulating layer 218 as in the case of theinsulating layer 216.

By providing the light-emitting element 40, each transistor, and thelike between the insulating layers 216 and 217 functioning as barrierlayers in such a manner, the touch panel module 10 can have highreliability.

The above is the description of Modification Example.

[Example of Manufacturing Method]

Here, a method for manufacturing a flexible touch panel is described.

For convenience, a structure including a pixel and a circuit, astructure including an optical member such as a color filter, astructure including an electrode or a wiring of a touch sensor, or thelike is referred to as an element layer. An element layer includes adisplay element, for example, and may include a wiring electricallyconnected to a display element or an element such as a transistor usedin a pixel or a circuit in addition to the display element.

Here, a support body (e.g., the substrate 171 or the substrate 172 inFIG. 41 and FIG. 42) with an insulating surface where an element layeris formed is referred to as a substrate.

As a method for forming an element layer over a flexible substrateprovided with an insulating surface, there are a method in which anelement layer is formed directly over a substrate, and a method in whichan element layer is formed over a supporting base material that isdifferent from the substrate and then the element layer is separatedfrom the supporting base material and transferred to the substrate.

In the case where a material of the substrate can withstand heatingtemperature in a process for forming the element layer, it is preferablethat the element layer be formed directly over the substrate, in whichcase a manufacturing process can be simplified. At this time, theelement layer is preferably formed in a state where the substrate isfixed to a supporting base material, in which case transfer thereof inan apparatus and between apparatuses can be easy.

In the case of employing the method in which the element layer is formedover the supporting base material and then transferred to the substrate,first, a separation layer and an insulating layer are stacked over thesupporting base material, and then the element layer is formed over theinsulating layer. Next, the element layer is separated from thesupporting base material and then transferred to the substrate. At thistime, selected is a material with which separation at an interfacebetween the supporting base material and the separation layer, at aninterface between the separation layer and the insulating layer, or inthe separation layer occurs.

For example, it is preferable that a stacked layer of a layer includinga high-melting-point metal material, such as tungsten, and a layerincluding an oxide of the metal material be used as the separationlayer, and a stacked layer of a plurality of layers, such as a siliconnitride layer, a silicon oxynitride layer, and a silicon nitride oxidelayer be used as the insulating layer over the separation layer. The useof the high-melting-point metal material is preferable because thedegree of freedom of the process for forming the element layer can beincreased.

The separation may be performed by application of mechanical power, byetching of the separation layer, by dripping of a liquid into part ofthe separation interface to penetrate the entire separation interface,or the like. Alternatively, separation may be performed by heating theseparation interface by utilizing a difference in thermal expansioncoefficient.

The separation layer is not necessarily provided in the case whereseparation can occur at an interface between the supporting basematerial and the insulating layer. For example, glass and an organicresin such as polyimide can be used as the supporting base material andthe insulating layer, respectively. In that case, a separation triggermay be formed by locally heating part of the organic resin with laserlight or the like, or by physically cutting part of or making a holethrough the organic resin with a sharp tool, for example, so thatseparation may be performed at an interface between the glass and theinsulating layer. Alternatively, a metal layer may be provided betweenthe supporting base material and the insulating layer formed of anorganic resin, and separation may be performed at the interface betweenthe metal layer and the insulating layer formed of an organic resin byheating the metal layer by feeding current to the metal layer. A layerof a light-absorbing material (e.g., a metal, a semiconductor, or aninsulator) may be provided between the supporting base material and theinsulating layer formed of an organic resin and locally heated withlaser light or the like to form a separation trigger. In these methods,the insulating layer formed of an organic resin can be used as asubstrate.

In the structure shown in FIG. 41, for example, a first separation layerand the insulating layer 216 are formed in this order over a firstsupporting base material, and then components in a layer over the firstseparation layer and the insulating layer 216 are formed. Next, thefirst supporting base material and the substrate 172 are attached toeach other with the adhesive layer 141. After that, separation at aninterface between the first separation layer and the insulating layer216 is conducted so that the first supporting base material and thefirst separation layer are removed, and then the substrate 171 isattached to the insulating layer 216 with the adhesive layer 251.

In the structure shown in FIG. 42, for example, a first separation layerand the insulating layer 216 are formed in this order over a firstsupporting base material, and then components in a layer over the firstseparation layer and the insulating layer 216 are formed. Separately, asecond separation layer and the insulating layer 218 are formed in thisorder over a second supporting base material, and then components in alayer over the second separation layer and the insulating layer 218 areformed. Next, the first supporting base material and the secondsupporting base material are attached to each other with the adhesivelayer 141. After that, separation at an interface between the secondseparation layer and the insulating layer 218 is conducted so that thesecond supporting base material and the second separation layer areremoved, and then the substrate 172 is attached to the insulating layer218 with the adhesive layer 252. Furthermore, separation at an interfacebetween the first separation layer and the insulating layer 216 isconducted so that the first supporting base material and the firstseparation layer are removed, and then the substrate 171 is attached tothe insulating layer 216 with the adhesive layer 251. Note that eitherside may be subjected to separation and attachment first.

The above is the description of a manufacturing method of a flexibletouch panel.

[Components]

The above components are described below.

[Substrate]

A substrate having a flat surface can be used as the substrate includedin the touch panel. The substrate on the side from which light from thedisplay element is extracted is formed using a material that transmitsthe light. For example, a material such as glass, quartz, ceramics,sapphire, or an organic resin can be used.

The weight and thickness of the touch panel can be decreased by using athin substrate. A flexible touch panel can be obtained by using asubstrate that is thin enough to have flexibility.

As the glass, for example, non-alkali glass, barium borosilicate glass,aluminoborosilicate glass, or the like can be used.

Since the substrate through which light emission is not extracted doesnot need to have a light-transmitting property, a metal substrate or thelike can be used in addition to the above-mentioned substrates. A metalmaterial and an alloy material, which have high thermal conductivity,are preferable because they can easily conduct heat to the wholesubstrate and accordingly can prevent a local temperature rise in thetouch panel. To obtain flexibility and bendability, the thickness of ametal substrate is preferably greater than or equal to 10 μm and lessthan or equal to 200 μm, more preferably greater than or equal to 20 μmand less than or equal to 50 μm.

Although there is no particular limitation on a material of a metalsubstrate, it is favorable to use, for example, a metal such asaluminum, copper, and nickel, an aluminum alloy, or an alloy such asstainless steel.

It is preferable to use a substrate subjected to insulation treatment,e.g., a metal substrate whose surface is oxidized or provided with aninsulating film. An insulating film may be formed by, for example, acoating method such as a spin-coating method and a dipping method, anelectrodeposition method, an evaporation method, or a sputtering method.An oxide film may be formed over the substrate surface by a known methodsuch as an anodic oxidation method, exposing to or heating in an oxygenatmosphere, or the like.

Examples of a material that has flexibility and transmits visible lightinclude flexible glass, polyester resins such as polyethyleneterephthalate (PET) and polyethylene naphthalate (PEN), apolyacrylonitrile resin, a polyimide resin, a polymethyl methacrylateresin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, apolyamide resin, a cycloolefin resin, a polystyrene resin, a polyamideimide resin, a polyvinyl chloride resin, and a polytetrafluoroethylene(PTFE). It is particularly preferable to use a material with a lowthermal expansion coefficient, for example, a material with a thermalexpansion coefficient lower than or equal to 30×10⁻⁶/K, such as apolyamide imide resin, a polyimide resin, or PET. A substrate in which afibrous body is impregnated with a resin (also referred to as prepreg)or a substrate whose thermal expansion coefficient is reduced by mixingan inorganic filler with an organic resin can also be used. A substrateusing such a material is lightweight, and thus a touch panel using thissubstrate can also be lightweight.

In the case where a fibrous body is included in the above material, ahigh-strength fiber of an organic compound or an inorganic compound isused as the fibrous body. The high-strength fiber is specifically afiber with a high tensile elastic modulus or a fiber with a high Young'smodulus. Typical examples thereof include a polyvinyl alcohol basedfiber, a polyester based fiber, a polyamide based fiber, a polyethylenebased fiber, an aramid based fiber, a polyparaphenylene benzobisoxazolefiber, a glass fiber, and a carbon fiber. As the glass fiber, glassfiber using E glass, S glass, D glass, Q glass, or the like can be used.These fibers may be used in a state of a woven fabric or a nonwovenfabric, and a structure body in which this fibrous body is impregnatedwith a resin and the resin is cured may be used as the flexiblesubstrate. The structure body including the fibrous body and the resinis preferably used as the flexible substrate, in which case thereliability against bending or breaking due to local pressure can beincreased.

A hard coat layer (e.g., a silicon nitride layer) by which a touch panelsurface is protected from damage, a layer (e.g., an aramid resin layer)that can disperse pressure, or the like may be stacked over the flexiblesubstrate. Furthermore, to suppress a decrease in lifetime of thedisplay element due to moisture and the like, an insulating film withlow water permeability may be stacked over the flexible substrate. Forexample, an inorganic insulating material such as silicon nitride,silicon oxynitride, aluminum oxide, or aluminum nitride can be used.

The substrate may be formed by stacking a plurality of layers. When aglass layer is used, a barrier property against water and oxygen can beimproved and thus a highly reliable touch panel can be provided.Alternatively, glass, metal, or the like that is thin enough to haveflexibility can be used as the substrate. Alternatively, a compositematerial where glass and a resin material are attached to each other maybe used.

A substrate in which a glass layer, an adhesive layer, and an organicresin layer are stacked from the side closer to the display element canbe used, for example. The thickness of the glass layer is greater thanor equal to 20 μm and less than or equal to 200 μm, preferably greaterthan or equal to 25 μm and less than or equal to 100 μm. With such athickness, the glass layer can have both a high barrier property againstwater and oxygen and high flexibility. The thickness of the organicresin layer is greater than or equal to 10 μm and less than or equal to200 μm, preferably greater than or equal to 20 μm and less than or equalto 50 μm. Providing such an organic resin layer, occurrence of a crackor a break in the glass layer can be suppressed and mechanical strengthcan be improved. With the substrate that includes such a compositematerial of a glass material and an organic resin, a highly reliableflexible touch panel can be provided.

[Transistor]

The transistor includes a conductive layer functioning as the gateelectrode, the semiconductor layer, a conductive layer functioning asthe source electrode, a conductive layer functioning as the drainelectrode, and an insulating layer functioning as the gate insulatinglayer. In the above, a bottom-gate transistor is used.

Note that there is no particular limitation on the structure of thetransistor included in the touch panel of one embodiment of the presentinvention. For example, a planar transistor, a staggered transistor, oran inverted staggered transistor may be used. A top-gate transistor or abottom-gate transistor may be used. Gate electrodes may be providedabove and below a channel.

There is no particular limitation on the crystallinity of asemiconductor material used for the transistors, and an amorphoussemiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a polycrystalline semiconductor, asingle-crystal semiconductor, or a semiconductor partly includingcrystal regions) may be used. It is preferable that a semiconductorhaving crystallinity be used, in which case deterioration of thetransistor characteristics can be suppressed.

As a semiconductor material for the semiconductor layer of thetransistor, an element of Group 14 (e.g., silicon or germanium), acompound semiconductor, or an oxide semiconductor can be used, forexample. Typically, a semiconductor containing silicon, a semiconductorcontaining gallium arsenide, an oxide semiconductor containing indium,or the like can be used.

In particular, an oxide semiconductor having a wider band gap thansilicon is preferably used. A semiconductor material having a wider bandgap and a lower carrier density than silicon is preferably used becauseoff-state leakage current of the transistor can be reduced.

As the semiconductor layer, it is particularly preferable to use anoxide semiconductor film (also referred to as CAAC-OS (a c-axis alignedcrystalline oxide semiconductor or a c-axis aligned and a-b-planeanchored crystalline oxide semiconductor)) including a plurality ofcrystal parts whose c-axes are aligned substantially perpendicular to asurface on which the semiconductor layer is formed or the top surface ofthe semiconductor layer and in which a grain boundary is not observedbetween adjacent crystal parts.

There is no grain boundary in such an oxide semiconductor; therefore,generation of a crack in an oxide semiconductor film which is caused bystress when a display panel is bent is prevented. Therefore, such anoxide semiconductor can be preferably used for a flexible touch panelwhich is used in a bent state, or the like.

Moreover, the use of such an oxide semiconductor with crystallinity forthe semiconductor layer makes it possible to provide a highly reliabletransistor in which a change in the electrical characteristics issuppressed.

A transistor with an oxide semiconductor whose band gap is larger thanthe band gap of silicon can hold charges stored in a capacitor that isseries-connected to the transistor for a long time, owing to the lowoff-state current of the transistor. When such a transistor is used fora pixel, operation of a driver circuit can be stopped while a gray scaleof each pixel is maintained. As a result, a display device withextremely low power consumption can be obtained.

The semiconductor layer preferably includes, for example, a filmrepresented by an In-M-Zn oxide that contains at least indium, zinc, andM (a metal such as aluminum, titanium, gallium, germanium, yttrium,zirconium, lanthanum, cerium, tin, neodymium, or hafnium). In order toreduce variations in electrical characteristics of the transistorincluding the oxide semiconductor, the oxide semiconductor preferablycontains a stabilizer in addition to indium, zinc, and M.

Examples of the stabilizer, including metals that can be used as M, aregallium, tin, hafnium, aluminum, and zirconium. As another stabilizer,lanthanoid such as lanthanum, cerium, praseodymium, neodymium, samarium,europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium,ytterbium, or lutetium can be given.

As an oxide semiconductor included in the semiconductor layer, any ofthe following can be used, for example: an In—Ga—Zn-based oxide, anIn—Al—Zn-based oxide, an In—Sn—Zn-based oxide, an In—Hf—Zn-based oxide,an In—La—Zn-based oxide, an In—Ce—Zn-based oxide, an In—Pr—Zn-basedoxide, an In—Nd—Zn-based oxide, an In—Sm—Zn-based oxide, anIn—Eu—Zn-based oxide, an In—Gd—Zn-based oxide, an In—Tb—Zn-based oxide,an In—Dy—Zn-based oxide, an In—Ho—Zn-based oxide, an In—Er—Zn-basedoxide, an In—Tm—Zn-based oxide, an In—Yb—Zn-based oxide, anIn—Lu—Zn-based oxide, an In—Sn—Ga—Zn-based oxide, an In—Hf—Ga—Zn-basedoxide, an In—Al—Ga—Zn-based oxide, an In—Sn—Al—Zn-based oxide, anIn—Sn—Hf—Zn-based oxide, and an In—Hf—Al—Zn-based oxide.

Note that here, for example, an “In—Ga—Zn-based oxide” means an oxidecontaining In, Ga, and Zn as its main components, and there is nolimitation on the ratio of In:Ga:Zn. The In—Ga—Zn-based oxide maycontain another metal element in addition to In, Ga, and Zn.

The semiconductor layer and the conductive layer may include the samemetal elements contained in the above oxides. The use of the same metalelements for the semiconductor layer and the conductive layer can reducethe manufacturing cost. For example, when metal oxide targets with thesame metal composition are used, the manufacturing cost can be reduced,and the same etching gas or the same etchant can be used in processingthe semiconductor layer and the conductive layer. Note that even whenthe semiconductor layer and the conductive layer include the same metalelements, they have different compositions in some cases. For example, ametal element in a film is released during the manufacturing process ofthe transistor and the capacitor, which might result in different metalcompositions.

In the case where the semiconductor layer is an In-M-Zn oxide, when Znand O are eliminated from consideration, the proportions of In and Mwhen the summation of In and M is assumed to be 100 atomic % arepreferably as follows: the atomic percentage of In is higher than 25atomic % and the atomic percentage of M is lower than 75 atomic %, morepreferably, the atomic percentage of In is higher than 34 atomic % andthe atomic percentage of M is lower than 66 atomic %.

The energy gap of the semiconductor layer is 2 eV or more, preferably2.5 eV or more, more preferably 3 eV or more. With the use of an oxidesemiconductor having such a wide energy gap, the off-state current ofthe transistor can be reduced.

The thickness of the semiconductor layer is greater than or equal to 3nm and less than or equal to 200 nm, preferably greater than or equal to3 nm and less than or equal to 100 nm, more preferably greater than orequal to 3 nm and less than or equal to 50 nm.

In the case where the semiconductor layer contains an In-M-Zn oxide, itis preferable that the atomic ratio of metal elements of a sputteringtarget used for forming a film of the In-M-Zn oxide satisfy In≥M andZn≥M. As the atomic ratio of metal elements of such a sputtering target,In:M:Zn=1:1:1, In:M:Zn=1:1:1.2, In:M:Zn=3:1:2, and In:M:Zn=4:2:3 arepreferable. Note that the atomic ratio of metal elements in the formedsemiconductor layer varies from the above atomic ratio of metal elementsof the sputtering target within a range of ±40% as an error.

An oxide semiconductor film with low carrier density is used as thesemiconductor layer. For example, the semiconductor layer is an oxidesemiconductor film whose carrier density is lower than or equal to1×10¹⁷/cm³, preferably lower than or equal to 1×10¹⁵/cm³, morepreferably lower than or equal to 1×10¹³/cm³, still more preferablylower than or equal to 1×10¹¹/cm³. Such an oxide semiconductor isreferred to as a highly purified intrinsic or substantially highlypurified intrinsic oxide semiconductor. The oxide semiconductor has lowimpurity concentration and a low density of defect states and can thusbe referred to as an oxide semiconductor having stable characteristics.

Note that, without limitation to those described above, a material withan appropriate composition may be used depending on requiredsemiconductor characteristics and electrical characteristics (e.g.,field-effect mobility and threshold voltage) of a transistor. To obtainthe required semiconductor characteristics of the transistor, it ispreferable that the carrier density, the impurity concentration, thedefect density, the atomic ratio between a metal element and oxygen, theinteratomic distance, the density, and the like of the semiconductorlayer be set to appropriate values.

When silicon or carbon that is one of elements belonging to Group 14 iscontained in the semiconductor layer, oxygen vacancies are increased inthe semiconductor layer, and the semiconductor layer becomes n-type.Thus, the concentration of silicon or carbon (measured by secondary ionmass spectrometry) in the semiconductor layer is lower than or equal to2×10¹⁸ atoms/cm³, preferably lower than or equal to 2×10¹⁷ atoms/cm³.

Alkali metal and alkaline earth metal might generate carriers whenbonded to an oxide semiconductor, in which case the off-state current ofthe transistor might be increased. Therefore, the concentration ofalkali metal or alkaline earth metal of the semiconductor layer, whichis measured by secondary ion mass spectrometry, is lower than or equalto 1×10¹⁸ atoms/cm³, preferably lower than or equal to 2×10¹⁶ atoms/cm³.

When nitrogen is contained in the semiconductor layer, electrons servingas carriers are generated and the carrier density increases, so that thesemiconductor layer easily becomes n-type. Thus, a transistor includingan oxide semiconductor which contains nitrogen is likely to be normallyon. For example, the concentration of nitrogen which is measured bysecondary ion mass spectrometry is preferably set to lower than or equalto 5×10¹⁸ atoms/cm³.

The semiconductor layer may have a non-single-crystal structure, forexample. The non-single-crystal structure includes CAAC-OS, apolycrystalline structure, a microcrystalline structure, or an amorphousstructure, for example. Among the non-single-crystal structures, anamorphous structure has the highest density of defect states, whereasCAAC-OS has the lowest density of defect states.

The semiconductor layer may have an amorphous structure, for example. Anoxide semiconductor film having an amorphous structure has disorderedatomic arrangement and no crystalline component, for example.Alternatively, an oxide film having an amorphous structure has, forexample, an absolutely amorphous structure and no crystal part.

Note that the semiconductor layer may be a mixed film including two ormore of the following: a region having an amorphous structure, a regionhaving a microcrystalline structure, a region having a polycrystallinestructure, a region of CAAC-OS, and a region having a single-crystalstructure. The mixed film has, for example, a single-layer structure ora stacked-layer structure including two or more of the above regions insome cases.

Alternatively, silicon is preferably used as a semiconductor in which achannel of a transistor is formed. Although amorphous silicon may beused as silicon, silicon having crystallinity is particularlypreferable. For example, microcrystalline silicon, polycrystallinesilicon, single-crystal silicon, or the like is preferably used. Inparticular, polycrystalline silicon can be formed at a lower temperaturethan single-crystal silicon and has higher field effect mobility andhigher reliability than amorphous silicon. When such a polycrystallinesemiconductor is used for a pixel, the aperture ratio of the pixel canbe improved. Even in the case of a high-definition display panel, a gatedriver circuit and a source driver circuit can be formed over asubstrate over which the pixels are formed, and the number of componentsof an electronic device can be reduced.

The bottom-gate transistor described in this embodiment is preferablebecause the number of manufacturing steps can be reduced. When amorphoussilicon, which can be formed at a lower temperature than polycrystallinesilicon, is used for the semiconductor layer, materials with low heatresistance can be used for a wiring, an electrode, or a substrate belowthe semiconductor layer, so that the range of choices of materials canbe widened. For example, an extremely large glass substrate can befavorably used. Meanwhile, the top-gate transistor described in thisembodiment is preferable because an impurity region is easily formed ina self-aligned manner and variation in characteristics can be reduced.In that case, the use of polycrystalline silicon, single-crystalsilicon, or the like is particularly preferable.

[Conductive Layer]

As a gate, a source, and a drain of a transistor, and a wiring or anelectrode included in a touch panel, any of metals such as aluminum,titanium, chromium, nickel, copper, yttrium, zirconium, molybdenum,silver, tantalum, and tungsten, or an alloy containing any of thesemetals as its main component can be used. A single-layer structure ormulti-layer structure including a film containing any of these materialscan be used. For example, the following structures can be given: asingle-layer structure of an aluminum film containing silicon, atwo-layer structure in which an aluminum film is stacked over a titaniumfilm, a two-layer structure in which an aluminum film is stacked over atungsten film, a two-layer structure in which a copper film is stackedover a copper-magnesium-aluminum alloy film, a two-layer structure inwhich a copper film is stacked over a titanium film, a two-layerstructure in which a copper film is stacked over a tungsten film, athree-layer structure in which a titanium film or a titanium nitridefilm, an aluminum film or a copper film, and a titanium film or atitanium nitride film are stacked in this order, and a three-layerstructure in which a molybdenum film or a molybdenum nitride film, analuminum film or a copper film, and a molybdenum film or a molybdenumnitride film are stacked in this order. Note that a transparentconductive material such as indium oxide, tin oxide, or zinc oxide maybe used. Copper containing manganese is preferably used becausecontrollability of a shape by etching is increased.

As a light-transmitting conductive material, a conductive oxide such asindium oxide, indium tin oxide, indium zinc oxide, zinc oxide, or zincoxide to which gallium is added, or graphene can be used. Alternatively,a metal material such as gold, silver, platinum, magnesium, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, ortitanium, or an alloy material containing any of these metal materialscan be used. Alternatively, a nitride of the metal material (e.g.,titanium nitride) or the like may be used. In the case of using themetal material or the alloy material (or the nitride thereof), thethickness is set small enough to be able to transmit light.Alternatively, a stack of any of the above materials can be used as theconductive layer. For example, a stacked film of indium tin oxide and analloy of silver and magnesium is preferably used because theconductivity can be increased. They can also be used for conductivelayers such as a variety of wirings and electrodes included in a touchpanel, and an electrode (e.g., a pixel electrode or a common electrode)included in a display element.

[Insulating Layer]

Examples of an insulating material that can be used for the insulatinglayers, the overcoat, the spacer, and the like include a resin such asacrylic or epoxy resin, a resin having a siloxane bond, and an inorganicinsulating material such as silicon oxide, silicon oxynitride, siliconnitride oxide, silicon nitride, or aluminum oxide.

The light-emitting element is preferably provided between a pair ofinsulating films with low water permeability, in which case impuritiessuch as water can be prevented from entering the light-emitting element.Thus, a decrease in device reliability can be prevented.

As an insulating film with low water permeability, a film containingnitrogen and silicon (e.g., a silicon nitride film or a silicon nitrideoxide film), a film containing nitrogen and aluminum (e.g., an aluminumnitride film), or the like can be used. Alternatively, a silicon oxidefilm, a silicon oxynitride film, an aluminum oxide film, or the like canbe used.

For example, the water vapor transmittance of the insulating film withlow water permeability is lower than or equal to 1×10⁻⁵ [g/m²·day],preferably lower than or equal to 1×10⁻⁶ [g/m²·day], further preferablylower than or equal to 1×10⁻⁷ [g/m²·day], still further preferably lowerthan or equal to 1×10⁻⁸ [g/m²·day].

[Light-Emitting Element]

As the light-emitting element, a self-luminous element can be used, andan element whose luminance is controlled by current or voltage isincluded in the category of the light-emitting element. For example, alight-emitting diode (LED), an organic EL element, an inorganic ELelement, or the like can be used.

The light-emitting element may be a top emission, bottom emission, ordual emission light-emitting element. A conductive film that transmitsvisible light is used as the electrode through which light is extracted.A conductive film that reflects visible light is preferably used as theelectrode through which light is not extracted.

The EL layer includes at least a light-emitting layer. In addition tothe light-emitting layer, the EL layer may further include one or morelayers containing any of a substance with a high hole-injectionproperty, a substance with a high hole-transport property, ahole-blocking material, a substance with a high electron-transportproperty, a substance with a high electron-injection property, asubstance with a bipolar property (a substance with a high electron- andhole-transport property), and the like.

Either a low molecular compound or a high molecular compound can be usedfor the EL layer, and an inorganic compound may also be used. The layersincluded in the EL layer can be formed by any of the following methods:an evaporation method (including a vacuum evaporation method), atransfer method, a printing method, an inkjet method, a coating method,and the like.

When a voltage higher than the threshold voltage of the light-emittingelement is applied between the anode and the cathode, holes are injectedto the EL layer from the anode side and electrons are injected to the ELlayer from the cathode side. The injected electrons and holes arerecombined in the EL layer, so that a light-emitting substance containedin the EL layer emits light.

In the case where a light-emitting element emitting white light is usedas the light-emitting element, the EL layer preferably contains two ormore kinds of light-emitting substances. For example, light-emittingsubstances are selected so that two or more light-emitting substancesemit complementary colors to obtain white light emission. Specifically,it is preferable to contain two or more light-emitting substancesselected from light-emitting substances emitting light of red (R), green(G), blue (B), yellow (Y), orange (O), and the like and light-emittingsubstances emitting light containing two or more of spectral componentsof R, G, and B. The light-emitting element preferably emits light with aspectrum having two or more peaks in the wavelength range of a visiblelight region (e.g., 350 nm to 750 nm). An emission spectrum of amaterial emitting light having a peak in the wavelength range of ayellow light preferably includes spectral components also in thewavelength range of a green light and a red light.

A light-emitting layer containing a light-emitting material emittinglight of one color and a light-emitting layer containing alight-emitting material emitting light of another color are preferablystacked in the EL layer. For example, the plurality of light-emittinglayers in the EL layer may be stacked in contact with each other or maybe stacked with a region not including any light-emitting materialtherebetween. For example, between a fluorescent layer and aphosphorescent layer, a region containing the same material as one inthe fluorescent layer or phosphorescent layer (for example, a hostmaterial or an assist material) and no light-emitting element may beprovided. This facilitates the manufacture of the light-emitting elementand reduces the drive voltage.

The light-emitting element may be a single element including one ELlayer or a tandem element in which a plurality of EL layers are stackedwith a charge generation layer therebetween.

The conductive film that transmits visible light can be formed using,for example, indium oxide, indium tin oxide, indium zinc oxide, zincoxide, or zinc oxide to which gallium is added. Alternatively, a film ofa metal material such as gold, silver, platinum, magnesium, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, ortitanium; an alloy containing any of these metal materials; or a nitrideof any of these metal materials (e.g., titanium nitride) can be usedwhen formed thin so as to have a light-transmitting property.Alternatively, a stack of any of the above materials can be used as theconductive layer. For example, a stacked film of indium tin oxide and analloy of silver and magnesium is preferably used, in which caseconductivity can be increased. Further alternatively, graphene or thelike may be used.

For the conductive film that reflects visible light, for example, ametal material, such as aluminum, gold, platinum, silver, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium or analloy including any of these metal materials can be used. Lanthanum,neodymium, germanium, or the like may be added to the metal material orthe alloy. Alternatively, an alloy containing aluminum (an aluminumalloy) such as an alloy of aluminum and titanium, an alloy of aluminumand nickel, or an alloy of aluminum and neodymium may be used.Alternatively, an alloy containing silver such as an alloy of silver andcopper, an alloy of silver and palladium, or an alloy of silver andmagnesium may be used. An alloy of silver and copper is preferablebecause of its high heat resistance. Furthermore, when a metal film or ametal oxide film is stacked in contact with an aluminum film or analuminum alloy film, oxidation of the aluminum alloy film can besuppressed. Examples of a material for the metal film or the metal oxidefilm are titanium, titanium oxide, and the like. Alternatively, theconductive film having a property of transmitting visible light and afilm containing any of the above metal materials may be stacked. Forexample, a stack of silver and indium tin oxide, a stack of an alloy ofsilver and magnesium and indium tin oxide, or the like can be used.

The electrodes may be formed separately by an evaporation method or asputtering method. Alternatively, a discharging method such as an inkjetmethod, a printing method such as a screen printing method, or a platingmethod may be used.

[Adhesive Layer]

As the adhesive layer, a variety of curable adhesives such as a reactivecurable adhesive, a thermosetting adhesive, an anaerobic adhesive, and aphoto curable adhesive such as an ultraviolet curable adhesive can beused. Examples of these adhesives include an epoxy resin, an acrylicresin, a silicone resin, a phenol resin, a polyimide resin, an imideresin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB)resin, and an ethylene vinyl acetate (EVA) resin. In particular, amaterial with low moisture permeability, such as an epoxy resin, ispreferred. Alternatively, a two-component-mixture-type resin may beused. Further alternatively, an adhesive sheet or the like may be used.

Furthermore, the resin may include a drying agent. For example, asubstance that adsorbs water by chemical adsorption, such as oxide of analkaline earth metal (e.g., calcium oxide or barium oxide), can be used.Alternatively, a substance that adsorbs water by physical adsorption,such as zeolite or silica gel, may be used. The drying agent ispreferably included because it can prevent impurities such as water fromentering the element, thereby improving the reliability of the displaypanel.

In addition, it is preferable to mix a filler with a high refractiveindex or light-scattering member into the resin, in which case lightextraction efficiency can be enhanced. For example, titanium oxide,barium oxide, zeolite, zirconium, or the like can be used.

[Connection Layer]

As the connection layers, an anisotropic conductive film (ACF), ananisotropic conductive paste (ACP), or the like can be used.

[Coloring Layer]

As examples of a material that can be used for the coloring layers, ametal material, a resin material, and a resin material containing apigment or dye can be given.

[Light-Blocking Layer]

As examples of a material that can be used for the light-blocking layer,carbon black, a metal oxide, and a composite oxide containing a solidsolution of a plurality of metal oxides can be given. Stacked filmscontaining the material of the coloring layer can also be used for thelight-blocking layer. For example, a stacked-layer structure of a filmcontaining a material of a coloring layer which transmits light of acertain color and a film containing a material of a coloring layer whichtransmits light of another color can be employed. It is preferable thatthe coloring layer and the light-blocking layer be formed using the samematerial because the same manufacturing apparatus can be used and theprocess can be simplified.

The above is the description of each of the components.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 2

In this embodiment, an example of a driving method of an input device(touch sensor) which can be applied to the touch panel module of oneembodiment of the present invention will be described.

FIG. 43A is a block diagram illustrating the structure of a mutualcapacitive touch sensor. FIG. 43A illustrates a pulse voltage outputcircuit 601 and a current sensing circuit 602. Note that in FIG. 43A,six wirings X1 to X6 represent electrodes 621 to which a pulse voltageis applied, and six wirings Y1 to Y6 represent electrodes 622 that sensechanges in current. The number of such electrodes is not limited tothose illustrated in this example. FIG. 43A also illustrates a capacitor603 that is formed with the electrodes 621 and 622 overlapping with eachother or being provided close to each other. Note that functionalreplacement between the electrodes 621 and 622 is possible.

For example, the wiring 23 described in Embodiment 1 corresponds to oneof the electrode 621 and the electrode 622, and the wiring 24 describedin Embodiment 1 corresponds to the other of the electrode 621 and theelectrode 622.

The pulse voltage output circuit 601 is, for example, a circuit forsequentially inputting a pulse voltage to the wirings X1 to X6. Thecurrent sensing circuit 602 is a circuit for sensing current flowingthrough each of the wirings Y1-Y6, for example.

By application of a pulse voltage to one of the wirings X1 to X6, anelectric field is generated between the electrodes 621 and 622 of thecapacitor 603, and current flows through the electrode 622. Part of theelectric field generated between the electrodes is blocked when anobject such a finger or a stylus contacts or approaches the device, sothat the electric field intensity between the electrodes is changed.Consequently, the amount of current flowing through the electrode 622 ischanged.

For example, in the case where there is no approach or no contact of anobject, the amount of current flowing in each of the wirings Y1-Y6depends on the amount of capacitance of the capacitor 603. In the casewhere part of an electric field is blocked by the approach or contact ofan object, a decrease in the amount of current flowing in the wiringsY1-Y6 is sensed. The approach or contact of an object can be sensed byutilizing this change.

Sensing by the current sensing circuit 602 may be performed using anintegral value (time integral value) of current flowing in a wiring. Inthat case, sensing may be performed with an integrator circuit or thelike, for example. Alternatively, the peak current value may be sensed.In that case, for example, current may be converted into voltage, andthe peak voltage value may be sensed.

FIG. 43B is an example of a timing chart illustrating input and outputwaveforms in the mutual capacitive touch sensor in FIG. 43A. In FIG.43B, sensing in each row and each column is performed in one sensingperiod. FIG. 43B shows a period when the contact or approach of anobject is not sensed (when the touch sensor is not touched) and a periodwhen the contact or approach of an object is sensed (when the touchsensor is touched). Here, the wirings Y1-Y6 each show a waveform of avoltage corresponding to the amount of current to be sensed.

As shown in FIG. 43B, the wirings X1-X6 are sequentially supplied with apulse voltage. Accordingly, current flows in the wirings Y1-Y6. When thetouch sensor is not touched, substantially the same current flows in thewirings Y1-Y6 in accordance with a change in voltages of the wiringsX1-X6; thus, the wirings Y1-Y6 have similar output waveforms. Meanwhile,when the touch sensor is touched, current flowing in a wiring in aposition which an object contacts or approaches among the wirings Y1-Y6is reduced; thus, the output waveforms are changed as shown in FIG. 43B.

FIG. 43B illustrates an example where an object contacts or approachesthe intersection of the wiring X3 and the wiring Y3 or the vicinitythereof.

A change in current due to block of an electric field generated betweena pair of electrodes is sensed in this manner in a mutual capacitivetouch sensor, so that positional information of an object can beobtained. When the detection sensitivity is high, the coordinates of theobject can be determined even when the object is far from a detectionsurface (e.g., a surface of the touch panel).

By driving a touch panel by a method in which a display period of adisplay portion and a sensing period of a touch sensor do not overlapwith each other, the detection sensitivity of the touch sensor can beincreased. For example, a display period and a sensing period may beseparately provided in one display frame period. In that case, two ormore sensing periods are preferably provided in one frame period. Whenthe frequency of sensing is increased, the detection sensitivity can beincreased.

It is preferable that, as an example, the pulse voltage output circuit601 and the current sensing circuit 602 be formed in one IC chip. Forexample, the IC is preferably mounted on a touch panel or a substrate ina housing of an electronic device. In the case where the touch panel hasflexibility, parasitic capacitance might be increased in a bent portionof the touch panel, and the influence of noise might be increased. Inview of this, it is preferable to use an IC to which a driving methodless influenced by noise is applied. For example, it is preferable touse an IC to which a driving method capable of increasing a signal-noiseratio (S/N ratio) is applied.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 3

In this embodiment, an example of a transistor which can be used as thetransistor 70, the transistor 70 a, the transistor 70 b, the transistor201, the transistor 202, and the like described in the above embodimentswill be described with reference to drawings.

The touch panel module 10 of one embodiment of the present invention canbe fabricated by using a transistor with any of various transistors,such as a bottom-gate transistor or a top-gate transistor. Therefore, amaterial for a semiconductor layer or the structure of a transistor canbe easily changed depending on the existing production line.

[Bottom-Gate Transistor]

FIG. 44A1 is a cross-sectional view of a transistor 810 that is achannel-protective transistor, which is a type of bottom-gatetransistor. In FIG. 44A1, the transistor 810 is formed over a substrate771. The transistor 810 includes an electrode 746 over the substrate 771with an insulating layer 772 provided therebetween. The transistor 810includes a semiconductor layer 742 over the electrode 746 with aninsulating layer 726 provided therebetween. The electrode 746 canfunction as a gate electrode. The insulating layer 726 can function as agate insulating layer.

The transistor 810 includes an insulating layer 741 over a channelformation region in the semiconductor layer 742. The transistor 810includes an electrode 744 a and an electrode 744 b which are partly incontact with the semiconductor layer 742 and over the insulating layer726. The electrode 744 a can function as one of a source electrode and adrain electrode. The electrode 744 b can function as the other of thesource electrode and the drain electrode. Part of the electrode 744 aand part of the electrode 744 b are formed over the insulating layer741.

The insulating layer 741 can function as a channel protective layer.With the insulating layer 741 provided over the channel formationregion, the semiconductor layer 742 can be prevented from being exposedat the time of forming the electrodes 744 a and 744 b. Thus, the channelformation region in the semiconductor layer 742 can be prevented frombeing etched at the time of forming the electrodes 744 a and 744 b. Inaccordance with one embodiment of the present invention, a transistorwith favorable electrical characteristics can be provided.

The transistor 810 includes an insulating layer 728 over the electrode744 a, the electrode 744 b, and the insulating layer 741 and furtherincludes an insulating layer 729 over the insulating layer 728.

The insulating layer 772 can be formed using a material and a methodsimilar to those of insulating layers 722 and 705. Note that theinsulating layer 772 may be formed of a stack of insulating layers. Forexample, the semiconductor layer 742 can be formed using a material anda method similar to those of the semiconductor layer 708. Note that thesemiconductor layer 742 may be formed of a stack of semiconductorlayers. For example, the electrode 746 can be formed using a materialand a method similar to those of the electrode 706. Note that theelectrode 746 may be formed of a stack of conductive layers. Theinsulating layer 726 can be formed using a material and a method similarto those of the insulating layer 707. Note that the insulating layer 726may be formed of a stack of insulating layers. For example, theelectrodes 744 a and 744 b can be formed using a material and a methodsimilar to those of the electrode 714 or 715. Note that the electrodes744 a and 744 b may be formed of a stack of conductive layers. Forexample, the insulating layer 741 can be formed using a material and amethod similar to those of the insulating layer 726. Note that theinsulating layer 741 may be formed of a stack of insulating layers. Forexample, the insulating layer 728 can be formed using a material and amethod similar to those of the insulating layer 710. Note that theinsulating layer 728 may be formed of a stack of insulating layers. Forexample, the insulating layer 729 can be formed using a material and amethod similar to those of the insulating layer 711. Note that theinsulating layer 729 may be formed of a stack of insulating layers.

The electrode, the semiconductor layer, the insulating layer, and thelike used in the transistor disclosed in this embodiment can be formedusing a material and a method disclosed in any of the other embodiments.

In the case where an oxide semiconductor is used for the semiconductorlayer 742, a material capable of removing oxygen from part of thesemiconductor layer 742 to generate oxygen vacancies is preferably usedfor regions of the electrodes 724 a and 724 b that are in contact withat least the semiconductor layer 742. The carrier concentration in theregions of the semiconductor layer 742 where oxygen vacancies aregenerated is increased, so that the regions become n-type regions (n⁺layers). Accordingly, the regions can function as a source region and adrain region. When an oxide semiconductor is used for the semiconductorlayer 742, examples of the material capable of removing oxygen from thesemiconductor layer 742 to generate oxygen vacancies include tungstenand titanium.

Formation of the source region and the drain region in the semiconductorlayer 742 makes it possible to reduce contact resistance between thesemiconductor layer 742 and each of the electrodes 724 a and 724 b.Accordingly, the electric characteristics of the transistor, such as thefield-effect mobility and the threshold voltage, can be favorable.

In the case where a semiconductor such as silicon is used for thesemiconductor layer 742, a layer that functions as an n-typesemiconductor or a p-type semiconductor is preferably provided betweenthe semiconductor layer 742 and the electrode 724 a and between thesemiconductor layer 742 and the electrode 724 b. The layer thatfunctions as an n-type semiconductor or a p-type semiconductor canfunction as the source region or the drain region in the transistor.

The insulating layer 729 is preferably formed using a material that canprevent or reduce diffusion of impurities into the transistor from theoutside. The formation of the insulating layer 729 may also be omitted.

When an oxide semiconductor is used for the semiconductor layer 742,heat treatment may be performed before and/or after the insulating layer729 is formed. The heat treatment can fill oxygen vacancies in thesemiconductor layer 742 by diffusing oxygen contained in the insulatinglayer 729 or other insulating layers into the semiconductor layer 742.Alternatively, the insulating layer 729 may be formed while the heattreatment is performed, so that oxygen vacancies in the semiconductorlayer 742 can be filled.

Note that a CVD method can be generally classified into a plasmaenhanced CVD (PECVD) method using plasma, a thermal CVD (TCVD) methodusing heat, and the like. A CVD method can be further classified into ametal CVD (MCVD) method, a metal organic CVD (MOCVD) method, and thelike according to a source gas to be used.

Furthermore, an evaporation method can be generally classified into aresistance heating evaporation method, an electron beam evaporationmethod, a molecular beam epitaxy (MBE) method, a pulsed laser deposition(PLD) method, an ion beam assisted deposition (IBAD) method, an atomiclayer deposition (ALD) method, and the like.

By using a PECVD method, a high-quality film can be formed at arelatively low temperature. By using a deposition method that does notuse plasma for deposition, such as an MOCVD method or an evaporationmethod, a film with few defects can be formed because damage is noteasily caused on a surface on which the film is deposited.

A sputtering method is generally classified into a DC sputtering method,a magnetron sputtering method, an RF sputtering method, an ion beamsputtering method, an electron cyclotron resonance (ECR) sputteringmethod, a facing-target sputtering method, and the like.

In a facing-target sputtering method, plasma is confined betweentargets; thus, plasma damage to a substrate can be reduced. Furthermore,step coverage can be improved because the incident angle of a sputteredparticle to a substrate can be made smaller depending on the inclinationof a target.

A transistor 811 illustrated in FIG. 44A2 is different from thetransistor 810 in that an electrode 723 that can function as a back gateelectrode is provided over the insulating layer 729. The electrode 723can be formed using a material and a method similar to those of theelectrode 746.

In general, a back gate electrode is formed using a conductive layer andpositioned so that a channel formation region of a semiconductor layeris positioned between a gate electrode and the back gate electrode.Thus, the back gate electrode can function in a manner similar to thatof the gate electrode. The potential of the back gate electrode may bethe same as that of the gate electrode or may be a ground (GND)potential or a predetermined potential. By changing the potential of theback gate electrode independently of the potential of the gateelectrode, the threshold voltage of the transistor can be changed.

The electrode 746 and the electrode 723 can each function as a gateelectrode. Thus, the insulating layers 726, 728, and 729 can eachfunction as a gate insulating layer. The electrode 723 may also beprovided between the insulating layers 728 and 729.

In the case where one of the electrode 746 and the electrode 723 issimply referred to as a “gate electrode”, the other can be referred toas a “back gate electrode”. For example, in the transistor 811, in thecase where the electrode 723 is referred to as a “gate electrode”, theelectrode 746 is referred to as a “back gate electrode”. In the casewhere the electrode 723 is used as a “gate electrode”, the transistor811 is a kind of top-gate transistor. Alternatively, one of theelectrode 746 and the electrode 723 may be referred to as a “first gateelectrode”, and the other may be referred to as a “second gateelectrode”.

By providing the electrode 746 and the electrode 723 with thesemiconductor layer 742 provided therebetween and setting the potentialsof the electrode 746 and the electrode 723 to be the same, a region ofthe semiconductor layer 742 through which carriers flow is enlarged inthe film thickness direction; thus, the number of transferred carriersis increased. As a result, the on-state current and field-effectmobility of the transistor 811 are increased.

Therefore, the transistor 811 has a high on-state current for its area.That is, the area of the transistor 811 can be small for a requiredon-state current. In accordance with one embodiment of the presentinvention, the area of a transistor can be reduced. Therefore, inaccordance with one embodiment of the present invention, a semiconductordevice having a high degree of integration can be provided.

The gate electrode and the back gate electrode are formed usingconductive layers and thus each have a function of preventing anelectric field generated outside the transistor from influencing thesemiconductor layer in which the channel is formed (in particular, anelectric field blocking function against static electricity and thelike). When the back gate electrode is formed larger than thesemiconductor layer such that the semiconductor layer is covered withthe back gate electrode, the electric field blocking function can beenhanced.

Since the electrode 746 and the electrode 723 each have a function ofblocking an electric field generated outside, electric charge of chargedparticles and the like generated on the insulating layer 772 side orabove the electrode 723 do not influence the channel formation region inthe semiconductor layer 742. Thus, degradation by a stress test (e.g., anegative gate bias temperature (−GBT) stress test in which negativeelectric charge is applied to a gate) can be reduced. Furthermore, achange in gate voltage (rising voltage) at which on-state current startsflowing depending on drain voltage can be reduced. Note that this effectis obtained when the electrodes 746 and 723 have the same potential ordifferent potentials.

The BT stress test is one kind of acceleration test and can evaluate, ina short time, a change by long-term use (i.e., a change over time) incharacteristics of a transistor. In particular, the amount of change inthreshold voltage of a transistor before and after the BT stress test isan important indicator when examining the reliability of the transistor.As the change in the threshold voltage is smaller, the transistor hashigher reliability.

By providing the electrodes 746 and 723 and setting the potentials ofthe electrodes 746 and 723 to be the same, the amount of change inthreshold voltage is reduced. Accordingly, variations in electricalcharacteristics among a plurality of transistors are also reduced.

A transistor including a back gate electrode has a smaller change inthreshold voltage before and after a positive GBT stress test, in whichpositive electric charge is applied to a gate, than a transistorincluding no back gate electrode.

When the back gate electrode is formed using a light-blocking conductivefilm, light can be prevented from entering the semiconductor layer fromthe back gate electrode side. Therefore, photodegradation of thesemiconductor layer can be prevented, and deterioration in electricalcharacteristics of the transistor, such as a shift of the thresholdvoltage, can be prevented.

In accordance with one embodiment of the present invention, a transistorwith high reliability can be provided. Moreover, a semiconductor devicewith high reliability can be provided.

FIG. 44B1 is a cross-sectional view of a channel-protective transistor820 that is a type of bottom-gate transistor. The transistor 820 hassubstantially the same structure as the transistor 810 but is differentfrom the transistor 810 in that the insulating layer 741 covers an endportion of the semiconductor layer 742. The semiconductor layer 742 iselectrically connected to the electrode 744 a through an opening formedby selectively removing part of the insulating layer 741 which overlapswith the semiconductor layer 742. The semiconductor layer 742 iselectrically connected to the electrode 744 b through another openingformed by selectively removing part of the insulating layer 741 whichoverlaps with the semiconductor layer 742. A region of the insulatinglayer 741 which overlaps with the channel formation region can functionas a channel protective layer.

A transistor 821 illustrated in FIG. 44B2 is different from thetransistor 820 in that the electrode 723 that can function as a backgate electrode is provided over the insulating layer 729.

With the insulating layer 729, the semiconductor layer 742 can beprevented from being exposed at the time of forming the electrodes 744 aand 744 b. Thus, the semiconductor layer 742 can be prevented from beingreduced in thickness at the time of forming the electrodes 744 a and 744b.

The length between the electrode 744 a and the electrode 746 and thelength between the electrode 744 b and the electrode 746 in thetransistors 820 and 821 are larger than those in the transistors 810 and811. Thus, the parasitic capacitance generated between the electrode 744a and the electrode 746 can be reduced. Moreover, the parasiticcapacitance generated between the electrode 744 b and the electrode 746can be reduced. In accordance with one embodiment of the presentinvention, a transistor with favorable electrical characteristics can beprovided.

A transistor 825 illustrated in FIG. 44C 1 is a channel-etchedtransistor that is a type of bottom-gate transistor. In the transistor825, the electrodes 744 a and 744 b are formed without providing theinsulating layer 729. Thus, part of the semiconductor layer 742 that isexposed at the time of forming the electrodes 744 a and 744 b is etchedin some cases. However, since the insulating layer 729 is not provided,the productivity of the transistor can be increased.

A transistor 826 illustrated in FIG. 44C2 is different from thetransistor 825 in that the electrode 723 which can function as a backgate electrode is provided over the insulating layer 729.

[Top-Gate Transistor]

FIG. 45A1 is a cross-sectional view of a transistor 830 that is a typeof top-gate transistor. The transistor 830 includes the semiconductorlayer 742 over the insulating layer 772, the electrodes 744 a and 744 bthat are over the semiconductor layer 742 and the insulating layer 772and in contact with part of the semiconductor layer 742, the insulatinglayer 726 over the semiconductor layer 742 and the electrodes 744 a and744 b, and the electrode 746 over the insulating layer 726.

Since the electrode 746 overlaps with neither the electrode 744 a northe electrode 744 b in the transistor 830, the parasitic capacitancegenerated between the electrodes 746 and 744 a and the parasiticcapacitance generated between the electrodes 746 and 744 b can bereduced. After the formation of the electrode 746, an impurity 755 isintroduced into the semiconductor layer 742 using the electrode 746 as amask, so that an impurity region can be formed in the semiconductorlayer 742 in a self-aligned manner (see FIG. 45A3). In accordance withone embodiment of the present invention, a transistor with favorableelectrical characteristics can be provided.

The introduction of the impurity 755 can be performed with an ionimplantation apparatus, an ion doping apparatus, or a plasma treatmentapparatus.

As the impurity 755, for example, at least one kind of element of Group13 elements and Group 15 elements can be used. In the case where anoxide semiconductor is used for the semiconductor layer 742, it ispossible to use at least one kind of element of a rare gas, hydrogen,and nitrogen as the impurity 755.

A transistor 831 illustrated in FIG. 45A2 is different from thetransistor 830 in that the electrode 723 and the insulating layer 727are included. The transistor 831 includes the electrode 723 formed overthe insulating layer 772 and the insulating layer 727 formed over theelectrode 723. The electrode 723 can function as a back gate electrode.Thus, the insulating layer 727 can function as a gate insulating layer.The insulating layer 727 can be formed using a material and a methodsimilar to those of the insulating layer 726.

Like the transistor 811, the transistor 831 has a high on-state currentfor its area. That is, the area of the transistor 831 can be small for arequired on-state current. In accordance with one embodiment of thepresent invention, the area of a transistor can be reduced. Therefore,in accordance with one embodiment of the present invention, asemiconductor device having a high degree of integration can beprovided.

A transistor 840 illustrated in FIG. 45B1 is a type of top-gatetransistor. The transistor 840 is different from the transistor 830 inthat the semiconductor layer 742 is formed after the formation of theelectrodes 744 a and 744 b. A transistor 841 illustrated in FIG. 45B2 isdifferent from the transistor 840 in that the electrode 723 and theinsulating layer 727 are included. In the transistors 840 and 841, partof the semiconductor layer 742 is formed over the electrode 744 a andanother part of the semiconductor layer 742 is formed over the electrode744 b.

Like the transistor 811, the transistor 841 has a high on-state currentfor its area. That is, the area of the transistor 841 can be small for arequired on-state current. In accordance with one embodiment of thepresent invention, the area of a transistor can be reduced. Therefore,in accordance with one embodiment of the present invention, asemiconductor device having a high degree of integration can beprovided.

A transistor 842 illustrated in FIG. 46A1 is a type of top-gatetransistor. The transistor 842 is different from the transistor 830 or840 in that the electrodes 744 a and 744 b are formed after theformation of the insulating layer 729. The electrodes 744 a and 744 bare electrically connected to the semiconductor layer 742 throughopenings formed in the insulating layers 728 and 729.

Part of the insulating layer 726 that does not overlap with theelectrode 746 is removed, and the impurity 755 is introduced into thesemiconductor layer 742 using the electrode 746 and the insulating layer726 that is left as a mask, so that an impurity region can be formed inthe semiconductor layer 742 in a self-aligned manner (see FIG. 46A3).The transistor 842 includes a region where the insulating layer 726extends beyond an end portion of the electrode 746. The semiconductorlayer 742 in a region into which the impurity 755 is introduced throughthe insulating layer 726 has a lower impurity concentration than thesemiconductor layer 742 in a region into which the impurity 755 isintroduced without through the insulating layer 726. Thus, a lightlydoped drain (LDD) region is formed in a region adjacent to a portion ofthe semiconductor layer 742 which overlaps with the electrode 746.

A transistor 843 illustrated in FIG. 46A2 is different from thetransistor 842 in that the electrode 723 is included. The transistor 843includes the electrode 723 that is formed over the substrate 771 andoverlaps with the semiconductor layer 742 with the insulating layer 772provided therebetween. The electrode 723 can function as a back gateelectrode.

As in a transistor 844 illustrated in FIG. 46B1 and a transistor 845illustrated in FIG. 46B2, the insulating layer 726 in a region that doesnot overlap with the electrode 746 may be completely removed.Alternatively, as in a transistor 846 illustrated in FIG. 46C1 and atransistor 847 illustrated in FIG. 46C2, the insulating layer 726 may beleft.

In the transistors 842 to 847, after the formation of the electrode 746,the impurity 755 is introduced into the semiconductor layer 742 usingthe electrode 746 as a mask, so that an impurity region can be formed inthe semiconductor layer 742 in a self-aligned manner. In accordance withone embodiment of the present invention, a transistor with favorableelectrical characteristics can be provided. Furthermore, in accordancewith one embodiment of the present invention, a semiconductor devicehaving a high degree of integration can be provided.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 4

In this embodiment, a structure example of a touch panel moduleincluding a touch panel of one embodiment of the present invention andan IC will be described with reference to drawings.

FIG. 47 is a block diagram of a touch panel module 6500. The touch panelmodule 6500 includes a touch panel 6510 and an IC 6520.

The touch panel 6510 includes a display portion 6511, an input portion6512, and a scan line driver circuit 6513. The display portion 6511includes a plurality of pixels, a plurality of signal lines, and aplurality of scan lines and has a function of displaying an image. Theinput portion 6512 includes a plurality of sensor elements for sensingthe contact or approach of an object to the touch panel 6510 andfunctions as a touch sensor. The scan line driver circuit 6513 has afunction of outputting scan signals to the scan lines included in thedisplay portion 6511.

The display portion 6511 and the input portion 6512 are separatelyillustrated in the touch panel 6510 for simplicity; however, a so-calledin-cell touch panel having both a function of displaying an image and afunction of a touch sensor is preferable.

As a touch sensor that can be used for the input portion 6512, acapacitive touch sensor can be used. Examples of the capacitive touchsensor are a surface capacitive touch sensor and a projected capacitivetouch sensor. Examples of the projected capacitive touch sensor includea self-capacitive touch sensor and a mutual capacitive touch sensor. Theuse of a mutual capacitive touch sensor is preferable because multiplepoints can be sensed simultaneously.

Note that one embodiment of the present invention is not limitedthereto, and any of various sensors that can sense the approach orcontact of an object such as a finger or a stylus can be used as theinput portion 6512. For the touch sensor, in addition to a capacitivetype, a variety of types such as a resistive type, a surface acousticwave type, an infrared type, and an optical type can be used, forexample.

As typical examples of the in-cell touch panel, a semi-in-cell type anda full-in-cell type can be given. The semi-in-cell type refers to astructure in which an electrode or the like included in a touch sensoris provided over a substrate that supports a display element and acounter substrate or over the counter substrate. Meanwhile, afull-in-cell type refers to a structure in which an electrode or thelike included in a touch sensor is provided over a substrate thatsupports a display element. In the case of a full-in-cell touch panel, astructure of a counter substrate can be simplified, which is preferable.In particular, when an electrode included in a display element alsoserves as an electrode in a touch sensor in a full-in-cell touch sensor,a manufacturing process can be simplified and manufacturing cost can bereduced, which is preferable.

The resolution of the display portion 6511 is preferably as high as HD(number of pixels: 1280×720), FHD (number of pixels: 1920×1080), WQHD(number of pixels: 2560×1440), WQXGA (number of pixels: 2560×1600), 4K(number of pixels: 3840×2160), or 8K (number of pixels: 7680×4320). Inparticular, resolution of 4K, 8K, or higher is preferable. The pixeldensity (definition) of the pixels in the display portion 6511 is higherthan or equal to 300 ppi, preferably higher than or equal to 500 ppi,more preferably higher than or equal to 800 ppi, more preferably higherthan or equal to 1000 ppi, more preferably higher than or equal to 1200ppi. The display portion 6511 with such high resolution and highdefinition enables an increase in a realistic sensation, sense of depth,and the like in personal use such as portable use and home use.

The IC 6520 includes a circuit unit 6501, a signal line driver circuit6502, a sensor driver circuit 6503, and a sensing circuit 6504. Thecircuit unit 6501 includes a timing controller 6505, an image processingcircuit 6506, or the like.

The signal line driver circuit 6502 has a function of outputting a videosignal that is an analog signal to a signal line included in the displayportion 6511. For example, the signal line driver circuit 6502 caninclude a shift register circuit and a buffer circuit in combination.The touch panel 6510 may include a demultiplexer circuit connected to asignal line.

The sensor driver circuit 6503 has a function of outputting a signal fordriving a sensor element included in the input portion 6512. As thesensor driver circuit 6503, a shift register circuit and a buffercircuit can be used in combination, for example.

The sensing circuit 6504 has a function of outputting, to the circuitunit 6501, an output signal from the sensor element included in theinput portion 6512. The sensing circuit 6504 can include an amplifiercircuit and an analog-digital converter (ADC), for example. In thatcase, the sensing circuit 6504 converts an analog signal output from theinput portion 6512 into a digital signal to be output to the circuitunit 6501.

The image processing circuit 6506 included in the circuit unit 6501 hasa function of generating and outputting a signal for driving the displayportion 6511 of the touch panel 6510, a function of generating andoutputting a signal for driving the input portion 6512, and a functionof analyzing a signal output from the input portion 6512 and outputtingthe signal to a CPU 6540.

As specific examples, the image processing circuit 6506 has thefollowing functions: a function of generating a video signal inaccordance with an instruction from the CPU 6540; a function ofperforming signal processing on a video signal in accordance with thespecification of the display portion 6511, converting the signal into ananalog video signal, and supplying the converted signal to the signalline driver circuit 6502; a function of generating a driving signaloutput to the sensor driver circuit 6503 in accordance with aninstruction from the CPU 6540; and a function of analyzing a signalinput from the sensing circuit 6504 and outputting the analyzed signalto the CPU 6540 as positional information.

The timing controller 6505 may have a function of generating andoutputting a signal (e.g., a clock signal or a start pulse signal)output to the scan line driver circuit 6513 and the sensor drivercircuit 6503 on the basis of a synchronization signal included in avideo signal or the like on which the image processing circuit 6506performs processing. Furthermore, the timing controller 6505 may have afunction of generating and outputting a signal for determining timingwhen the sensing circuit 6504 outputs a signal. Here, the timingcontroller 6505 preferably outputs synchronized signals as the signaloutput to the scan line driver circuit 6513 and the signal output to thesensor driver circuit 6503. In particular, it is preferable that aperiod in which data in a pixel in the display portion 6511 is rewrittenand a period in which sensing is performed with the input portion 6512be separately provided. For example, the touch panel 6510 can be drivenby dividing one frame period into a period in which data in a pixel isrewritten and a period in which sensing is performed. Furthermore,detection sensitivity and detection accuracy can be increased, forexample, by providing two or more sensing periods in one frame period.

The image processing circuit 6506 can include a processor, for example.A microprocessor such as a digital signal processor (DSP) or a graphicsprocessing unit (GPU) can be used, for example. Furthermore, such amicroprocessor may be obtained with a programmable logic device (PLD)such as a field programmable gate array (FPGA) or a field programmableanalog array (FPAA). The image processing circuit 6506 interprets andexecutes instructions from various programs with the processor toprocess various kinds of data and control programs. The programsexecuted by the processor may be stored in a memory region included inthe processor or a memory device which is additionally provided.

A transistor which includes an oxide semiconductor in a channelformation region and has an extremely low off-state current can be usedin the display portion 6511 or the scan line driver circuit 6513included in the touch panel 6510, the circuit unit 6501, the signal linedriver circuit 6502, the sensor driver circuit 6503, or the sensingcircuit 6504 included in the IC 6520, the CPU 6540 provided outside thetouch panel module 6500, or the like. With the use of the transistorhaving an extremely low off-state current as a switch for holdingelectric charge (data) which flows into a capacitor serving as a memoryelement, a long data retention period can be ensured. For example, byutilizing the characteristic for a register or a cache memory of theimage processing circuit 6506, normally off computing is achieved wherethe image processing circuit 6506 operates only when needed and data onthe previous processing is stored in the memory element in the rest oftime; thus, power consumption of the touch panel module 6500 and anelectronic device on which the touch panel module 6500 is mounted can bereduced.

Although the structure where the circuit unit 6501 includes the timingcontroller 6505 and the image processing circuit 6506 is used here, theimage processing circuit 6506 itself or a circuit having a function ofpart of the image processing circuit 6506 may be provided outside the IC6520. Alternatively, the CPU 6540 may have a function of the imageprocessing circuit 6506 or part thereof. For example, the circuit unit6501 can include the signal line driver circuit 6502, the sensor drivercircuit 6503, the sensing circuit 6504, and the timing controller 6505.

Although the example where the IC 6520 includes the circuit unit 6501 isshown here, the structure where the circuit unit 6501 is not included inthe IC 6520 may be employed. In that case, the IC 6520 can include thesignal line driver circuit 6502, the sensor driver circuit 6503, and thesensing circuit 6504. For example, in the case where the touch panelmodule 6500 includes a plurality of ICs, the circuit unit 6501 may beseparately provided and a plurality of ICs 6520 without the circuit unit6501 may be provided, and alternatively, the IC 6520 and an IC includingonly the signal line driver circuit 6502 can be provided in combination.

When an IC has a function of driving the display portion 6511 of thetouch panel 6510 and a function of driving the input portion 6512 asdescribed above, the number of ICs mounted on the touch panel module6500 can be reduced; accordingly, cost can be reduced.

FIGS. 48A to 48C each are a schematic diagram of the touch panel module6500 on which the IC 6520 is mounted.

In FIG. 48A, the touch panel module 6500 includes a substrate 6531, acounter substrate 6532, a plurality of FPCs 6533, the IC 6520, ICs 6530,and the like. The display portion 6511, the input portion 6512, and thescan line driver circuits 6513 are provided between the substrate 6531and the counter substrate 6532. The IC 6520 and the ICs 6530 are mountedon the substrate 6531 by a COG method.

The IC 6530 is an IC in which only the signal line driver circuit 6502is provided in the above-described IC 6520 or an IC in which the signalline driver circuit 6502 and the circuit unit 6501 are provided in theabove-described IC 6520. The IC 6520 and the IC 6530 are supplied with asignal from the outside through the FPCs 6533. Furthermore, a signal canbe output to the outside from the IC 6520 or the IC 6530 through the FPC6533.

FIG. 48A illustrates an example where the display portion 6511 ispositioned between two scan line driver circuits 6513. The ICs 6530 areprovided in addition to the IC 6520. Such a structure is preferable inthe case where the display portion 6511 has extremely high resolution.

FIG. 48B illustrates an example where one IC 6520 and one FPC 6533 areprovided. It is preferable to bring functions into one IC 6520 in thismanner because the number of components can be reduced. In the examplein FIG. 48B, the scan line driver circuit 6513 is provided along a sideclose to the FPC 6533 among two short sides of the display portion 6511.

FIG. 48C illustrates an example where a printed circuit board (PCB) 6534on which the image processing circuit 6506 and the like are mounted isprovided. The ICs 6520 and 6530 over the substrate 6531 are electricallyconnected to the PCB 6534 through the FPCs 6533. The above-describedstructure without the image processing circuit 6506 can be applied tothe IC 6520.

In each of FIGS. 48A to 48C, the IC 6520 or the IC 6530 may be mountedon the FPC 6533, not on the substrate 6531. For example, the IC 6520 orthe IC 6530 may be mounted on the FPC 6533 by a chip on film (COF)method, a tape automated bonding (TAB) method, or the like.

A structure where the FPC 6533, the IC 6520 (and the IC 6530), or thelike is provided on a short side of the display portion 6511 asillustrated in FIGS. 48A and 48B enables the frame of the display deviceto be narrowed; thus, the structure is preferably used for electronicdevices such as smartphones, mobile phones, and tablet terminals, forexample. The structure with the PCB 6534 illustrated in FIG. 48C can bepreferably used for television devices, monitors, tablet terminals, orlaptop personal computers, for example.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 5

In this embodiment, a display module and electronic devices that includethe display device of one embodiment of the present invention or adisplay system will be described with reference to FIG. 49, FIGS. 50A to50H, FIGS. 51A and 51B, FIGS. 52A to 52H, FIGS. 53A1 to 53I, and FIGS.54A to 54E.

In a display module 8000 illustrated in FIG. 49, a touch panel 8004connected to an FPC 8003, a frame 8009, a printed board 8010, and abattery 8011 are provided between an upper cover 8001 and a lower cover8002.

The display panel, the touch panel, or the touch panel module of oneembodiment of the present invention can be used for the touch panel8004, for example.

The shapes and sizes of the upper cover 8001 and the lower cover 8002can be changed as appropriate in accordance with the size of the touchpanel 8004.

The touch panel 8004 can be a resistive touch panel or a capacitivetouch panel and may be formed so as to overlap with a display panel. Acounter substrate (sealing substrate) of the touch panel 8004 can have atouch panel function. A photosensor may be provided in each pixel of thetouch panel 8004 so that an optical touch panel can be obtained.

In the case of a transmissive or a semi-transmissive liquid crystalelement, a backlight 8007 may be provided as illustrated in FIG. 49. Thebacklight 8007 includes a light source 8008. Note that although astructure in which the light source 8008 is provided over the backlight8007 is illustrated in FIG. 49, one embodiment of the present inventionis not limited to this structure. For example, a structure in which thelight source 8008 is provided at an end portion of the backlight 8007and a light diffusion plate is further provided may be employed. Notethat the backlight 8007 needs not be provided in the case where aself-luminous light-emitting element such as an organic EL element isused or in the case where a reflective panel or the like is employed.

The frame 8009 protects a display panel 8006 and functions as anelectromagnetic shield for blocking electromagnetic waves generated bythe operation of the printed board 8010. The frame 8009 can alsofunction as a radiator plate.

The printed board 8010 is provided with a power supply circuit and asignal processing circuit for outputting a video signal and a clocksignal. As a power source for supplying electric power to the powersupply circuit, an external commercial power source or a power sourceusing the battery 8011 provided separately may be used. The battery 8011can be omitted in the case of using a commercial power source.

The touch panel 8004 can be additionally provided with a component suchas a polarizing plate, a retardation plate, or a prism sheet.

Electronic devices and lighting devices can be manufactured by using thedisplay panel, the light-emitting panel, the sensor panel, the touchpanel, the touch panel module, the input device, the display device, orthe input/output device of one embodiment of the present invention.Highly reliable electronic devices and lighting devices with curvedsurfaces can be manufactured by using the input device, the displaydevice, or the input/output device of one embodiment of the presentinvention. In addition, flexible and highly reliable electronic devicesand lighting devices can be manufactured by using the input device, thedisplay device, or the input/output device of one embodiment of thepresent invention. Furthermore, electronic devices and lighting devicesincluding touch sensors with improved detection sensitivity can bemanufactured by using the input device or the input/output device of oneembodiment of the present invention.

Examples of electronic devices include a television set (also referredto as a television or a television receiver), a monitor of a computer orthe like, a digital camera, a digital video camera, a digital photoframe, a mobile phone (also referred to as a mobile phone device), aportable game machine, a portable information terminal, an audioreproducing device, a large game machine such as a pachinko machine, andthe like.

In the case of having flexibility, the electronic device or the lightingdevice of one embodiment of the present invention can be incorporatedalong a curved inside/outside wall surface of a house or a building or acurved interior/exterior surface of a car.

Furthermore, the electronic device of one embodiment of the presentinvention may include a secondary battery. It is preferable that thesecondary battery be capable of being charged by contactless powertransmission.

As examples of the secondary battery, a lithium ion secondary batterysuch as a lithium polymer battery (lithium ion polymer battery) using agel electrolyte, a lithium ion battery, a nickel-hydride battery, anickel-cadmium battery, an organic radical battery, a lead-acid battery,an air secondary battery, a nickel-zinc battery, and a silver-zincbattery can be given.

The electronic device of one embodiment of the present invention mayinclude an antenna. When a signal is received by the antenna, theelectronic device can display an image, data, or the like on a displayportion. When the electronic device includes a secondary battery, theantenna may be used for contactless power transmission.

FIGS. 50A to 50H and FIGS. 51A and 51B illustrate electronic devices.These electronic devices can each include a housing 5000, a displayportion 5001, a speaker 5003, an LED lamp 5004, operation keys 5005(including a power switch or an operation switch), a connection terminal5006, a sensor 5007 (a sensor having a function of measuring force,displacement, position, speed, acceleration, angular velocity,rotational frequency, distance, light, liquid, magnetism, temperature,chemical substance, sound, time, hardness, electric field, current,voltage, electric power, radiation, flow rate, humidity, gradient,oscillation, odor, or infrared rays), a microphone 5008, and the like.

FIG. 50A illustrates a mobile computer, which can include a switch 5009,an infrared port 5010, and the like in addition to the above components.

FIG. 50B illustrates a portable image reproducing device provided with arecording medium (e.g., a DVD reproducing device), which can include asecond display portion 5002, a recording medium reading portion 5011,and the like in addition to the above components.

FIG. 50C illustrates a television device, which can include a stand 5012and the like in addition to the above components. The television devicecan be operated by an operation switch of the housing 5000 or a separateremote controller 5013. With operation keys of the remote controller5013, channels and volume can be controlled, and images displayed on thedisplay portion 5001 can be controlled. The remote controller 5013 maybe provided with a display portion for displaying data output from theremote controller 5013.

FIG. 50D illustrates a portable game machine, which can include therecording medium reading portion 5011 and the like in addition to theabove components.

FIG. 50E illustrates a digital camera that has a television receptionfunction and can include an antenna 5014, a shutter button 5015, animage receiving portion 5016, and the like in addition to the abovecomponents.

FIG. 50F illustrates a portable game machine, which can include thesecond display portion 5002, the recording medium reading portion 5011,and the like in addition to the above components.

FIG. 50G illustrates a portable television receiver, which can include acharger 5017 capable of transmitting and receiving signals, and the likein addition to the above components.

FIG. 50H illustrates a wrist-watch-type information terminal, which caninclude a band 5018, a clasp 5019, and the like in addition to the abovecomponents. The display portion 5001 mounted in the housing 5000 alsoserving as a bezel includes a non-rectangular display region. Thedisplay portion 5001 can display an icon 5020 indicating time, anothericon 5021, and the like.

FIG. 51A illustrates a digital signage. FIG. 51B illustrates a digitalsignage mounted on a cylindrical pillar.

The electronic devices illustrated in FIGS. 50A to 50H and FIGS. 51A and51B can have a variety of functions, for example, a function ofdisplaying a variety of information (e.g., a still image, a movingimage, and a text image) on a display portion, a touch panel function, afunction of displaying a calendar, date, time, and the like, a functionof controlling processing with a variety of software (programs), awireless communication function, a function of being connected to avariety of computer networks with a wireless communication function, afunction of transmitting and receiving a variety of data with a wirelesscommunication function, and a function of reading a program or datastored in a recording medium and displaying the program or data on adisplay portion. Furthermore, the electronic device including aplurality of display portions can have a function of displaying imageinformation mainly on one display portion while displaying textinformation mainly on another display portion, a function of displayinga three-dimensional image by displaying images where parallax isconsidered on a plurality of display portions, or the like. Furthermore,the electronic device including an image receiving portion can have afunction of photographing a still image, a function of photographing amoving image, a function of automatically or manually correcting aphotographed image, a function of storing a photographed image in arecording medium (an external recording medium or a recording mediumincorporated in the camera), a function of displaying a photographedimage on a display portion, or the like. Note that the functions of theelectronic devices illustrated in FIGS. 50A to 50H and FIGS. 51A and 51Bare not limited thereto, and the electronic devices can have a varietyof functions.

FIGS. 52A, 52B, 52C1, 52C2, 52D, and 52E illustrate examples of anelectronic device including a display portion 7000 with a curvedsurface. The display surface of the display portion 7000 is bent, andimages can be displayed on the bent display surface. The display portion7000 may be flexible.

The display portion 7000 can be formed using the display panel, thelight-emitting panel, the sensor panel, the touch panel, the displaydevice, the input/output device, or the like of one embodiment of thepresent invention. One embodiment of the present invention makes itpossible to provide a highly reliable electronic device having a curveddisplay portion.

FIG. 52A illustrates an example of a mobile phone. A mobile phone 7100includes a housing 7101, the display portion 7000, operation buttons7103, an external connection port 7104, a speaker 7105, a microphone7106, and the like.

The mobile phone 7100 illustrated in FIG. 52A includes a touch sensor inthe display portion 7000. Moreover, operations such as making a call andinputting a letter can be performed by touch on the display portion 7000with a finger, a stylus, or the like.

With the operation buttons 7103, power ON or OFF can be switched. Inaddition, types of images displayed on the display portion 7000 can beswitched; for example, switching from a mail creation screen to a mainmenu screen can be performed.

FIG. 52B illustrates an example of a television set. In a television set7200, the display portion 7000 is incorporated into a housing 7201.Here, the housing 7201 is supported by a stand 7203.

The television set 7200 illustrated in FIG. 52B can be operated with anoperation switch of the housing 7201 or a separate remote controller7211. The display portion 7000 may include a touch sensor. The displayportion 7000 can be operated by touching the display portion with afinger or the like. The remote controller 7211 may be provided with adisplay portion for displaying data output from the remote controller7211. With operation keys or a touch panel of the remote controller7211, channels and volume can be controlled and images displayed on thedisplay portion 7000 can be controlled.

The television set 7200 is provided with a receiver, a modem, and thelike. A general television broadcast can be received with the receiver.When the television set is connected to a communication network with orwithout wires via the modem, one-way (from a transmitter to a receiver)or two-way (between a transmitter and a receiver or between receivers)data communication can be performed.

FIGS. 52C1, 52C2, 52D, and 52E illustrate examples of a portableinformation terminal. Each of the portable information terminalsincludes a housing 7301 and the display portion 7000. Each of theportable information terminals may also include an operation button, anexternal connection port, a speaker, a microphone, an antenna, abattery, or the like. The display portion 7000 is provided with a touchsensor. An operation of the portable information terminal can beperformed by touching the display portion 7000 with a finger, a stylus,or the like.

FIG. 52C1 is a perspective view of a portable information terminal 7300.FIG. 52C2 is a top view of the portable information terminal 7300. FIG.52D is a perspective view of a portable information terminal 7310. FIG.52E is a perspective view of a portable information terminal 7320.

Each of the portable information terminals illustrated in thisembodiment functions as, for example, one or more of a telephone set, anotebook, and an information browsing system. Specifically, the portableinformation terminals each can be used as a smartphone. Each of theportable information terminals illustrated in this embodiment is capableof executing a variety of applications such as mobile phone calls,e-mailing, reading and editing texts, music reproduction, Internetcommunication, and a computer game, for example.

The portable information terminals 7300, 7310, and 7320 can displaycharacters and image information on its plurality of surfaces. Forexample, as illustrated in FIGS. 52C1 and 52D, three operation buttons7302 can be displayed on one surface, and information 7303 indicated bya rectangle can be displayed on another surface. FIGS. 52C1 and 52C2illustrate an example in which information is displayed at the top ofthe portable information terminal. FIG. 52D illustrates an example inwhich information is displayed on the side of the portable informationterminal. Information may be displayed on three or more surfaces of theportable information terminal. FIG. 52E illustrates an example whereinformation 7304, information 7305, and information 7306 are displayedon different surfaces.

Examples of the information include notification from a socialnetworking service (SNS), display indicating reception of an e-mail oran incoming call, the title of an e-mail or the like, the sender of ane-mail or the like, the date, the time, remaining battery, and thereception strength of an antenna. Alternatively, the operation button,an icon, or the like may be displayed instead of the information.

For example, a user of the portable information terminal 7300 can seethe display (here, the information 7303) on the portable informationterminal 7300 put in a breast pocket of his/her clothes.

Specifically, a caller's phone number, name, or the like of an incomingcall is displayed in a position that can be seen from above the portableinformation terminal 7300. Thus, the user can see the display withouttaking out the portable information terminal 7300 from the pocket anddecide whether to answer the call.

FIGS. 52F to 52H each illustrate an example of a lighting device havinga curved light-emitting portion.

The light-emitting portion included in each of the lighting devicesillustrated in FIGS. 52F to 52H can be manufactured using the displaypanel, the light-emitting panel, the sensor panel, the touch panel, thedisplay device, the input/output device, or the like of one embodimentof the present invention. According to one embodiment of the presentinvention, a highly reliable lighting device having a curvedlight-emitting portion can be provided.

A lighting device 7400 illustrated in FIG. 52F includes a light-emittingportion 7402 with a wave-shaped light-emitting surface and thus is agood-design lighting device.

A light-emitting portion 7412 included in a lighting device 7410illustrated in FIG. 52G has two convex-curved light-emitting portionssymmetrically placed. Thus, all directions can be illuminated with thelighting device 7410 as a center.

A lighting device 7420 illustrated in FIG. 52H includes a concave-curvedlight-emitting portion 7422. This is suitable for illuminating aspecific range because light emitted from the concave-curvedlight-emitting portion 7422 is collected to the front of the lightingdevice 7420. In addition, with this structure, a shadow is less likelyto be produced.

The light-emitting portion included in each of the lighting devices7400, 7410 and 7420 may be flexible. The light-emitting portion may befixed on a plastic member, a movable frame, or the like so that alight-emitting surface of the light-emitting portion can be bent freelydepending on the intended use.

The lighting devices 7400, 7410, and 7420 each include a stage 7401provided with an operation switch 7403 and the light-emitting portionsupported by the stage 7401.

Note that although the lighting device in which the light-emittingportion is supported by the stage is described as an example here, ahousing provided with a light-emitting portion can be fixed on a ceilingor suspended from a ceiling. Since the light-emitting surface can becurved, the light-emitting surface is curved to have a concave shape,whereby a particular region can be brightly illuminated, or thelight-emitting surface is curved to have a convex shape, whereby a wholeroom can be brightly illuminated.

FIGS. 53A1, 53A2, 53B, 53C, 53D, 53E, 53F, 53G, 53H, and 53I eachillustrate an example of a portable information terminal including adisplay portion 7001 having flexibility.

The display portion 7001 is manufactured using the display panel, thelight-emitting panel, the sensor panel, the touch panel, the displaydevice, the input/output device, or the like of one embodiment of thepresent invention. For example, a display device or an input/outputdevice that can be bent with a radius of curvature of greater than orequal to 0.01 mm and less than or equal to 150 mm can be used. Thedisplay portion 7001 may include a touch sensor so that the portableinformation terminal can be operated by touching the display portion7001 with a finger or the like. One embodiment of the present inventionmakes it possible to provide a highly reliable electronic deviceincluding a display portion having flexibility.

FIGS. 53A1 and 53A2 are a perspective view and a side view illustratingan example of the portable information terminal, respectively. Aportable information terminal 7500 includes a housing 7501, the displayportion 7001, a display portion tab 7502, operation buttons 7503, andthe like.

The portable information terminal 7500 includes a rolled flexibledisplay portion 7001 in the housing 7501.

The portable information terminal 7500 can receive a video signal with acontrol portion incorporated therein and can display the received videoon the display portion 7001. The portable information terminal 7500incorporates a battery. A terminal portion for connecting a connectormay be included in the housing 7501 so that a video signal or power canbe directly supplied from the outside with a wiring.

By pressing the operation buttons 7503, power ON/OFF, switching ofdisplayed videos, and the like can be performed. Although FIGS. 53A1,53A2, and 53B illustrate an example where the operation buttons 7503 arepositioned on a side surface of the portable information terminal 7500,one embodiment of the present invention is not limited thereto. Theoperation buttons 7503 may be placed on a display surface (a frontsurface) or a rear surface of the portable information terminal 7500.

FIG. 53B illustrates the portable information terminal 7500 in a statewhere the display portion 7001 is pulled out with the display portiontab 7502. Videos can be displayed on the display portion 7001 in thisstate. In addition, the portable information terminal 7500 may performdifferent displays in the state where part of the display portion 7001is rolled as shown in FIG. 53A1 and in the state where the displayportion 7001 is pulled out with the display portion tab 7502 as shown inFIG. 53B. For example, in the state shown in FIG. 53A1, the rolledportion of the display portion 7001 is put in a non-display state, whichresults in a reduction in power consumption of the portable informationterminal 7500.

A reinforcement frame may be provided for a side portion of the displayportion 7001 so that the display portion 7001 has a flat display surfacewhen pulled out.

Note that in addition to this structure, a speaker may be provided forthe housing so that sound is output with an audio signal receivedtogether with a video signal.

FIGS. 53C to 53E illustrate an example of a foldable portableinformation terminal. FIG. 53C illustrates a portable informationterminal 7600 that is opened. FIG. 53D illustrates the portableinformation terminal 7600 that is being opened or being folded. FIG. 53Eillustrates the portable information terminal 7600 that is folded. Theportable information terminal 7600 is highly portable when folded, andis highly browsable when opened because of a seamless large displayarea.

The display portion 7001 is supported by three housings 7601 joinedtogether by hinges 7602. By folding the portable information terminal7600 at a connection portion between two housings 7601 with the hinges7602, the portable information terminal 7600 can be reversibly changedin shape from an opened state to a folded state.

FIGS. 53F and 53G illustrate an example of a foldable portableinformation terminal. FIG. 53F illustrates a portable informationterminal 7650 that is folded so that the display portion 7001 is on theinside. FIG. 53G illustrates the portable information terminal 7650 thatis folded so that the display portion 7001 is on the outside. Theportable information terminal 7650 includes the display portion 7001 anda non-display portion 7651. When the portable information terminal 7650is not used, the portable information terminal 7650 is folded so thatthe display portion 7001 is on the inside, whereby the display portion7001 can be prevented from being contaminated or damaged.

FIG. 53H illustrates an example of a flexible portable informationterminal. A portable information terminal 7700 includes a housing 7701and the display portion 7001. The portable information terminal 7700 mayinclude buttons 7703 a and 7703 b which serve as input means, speakers7704 a and 7704 b which serve as sound output means, an externalconnection port 7705, a microphone 7706, or the like. A flexible battery7709 can be included in the portable information terminal 7700. Thebattery 7709 may be arranged to overlap with the display portion 7001,for example.

The housing 7701, the display portion 7001, the battery 7709 areflexible. Thus, it is easy to curve the portable information terminal7700 into a desired shape or to twist the portable information terminal7700. For example, the portable information terminal 7700 can be foldedso that the display portion 7001 is on the inside or on the outside. Theportable information terminal 7700 can be used in a rolled state. Sincethe housing 7701 and the display portion 7001 can be transformed freelyin this manner, the portable information terminal 7700 is less likely tobe broken even when the portable information terminal 7700 falls down orexternal stress is applied to the portable information terminal 7700.

The portable information terminal 7700 can be used conveniently invarious situations because the portable information terminal 7700 islightweight. For example, the portable information terminal 7700 can beused in the state where the upper portion of the housing 7701 issuspended by a clip or the like, or in the state where the housing 7701is fixed to a wall by magnets or the like.

FIG. 53I illustrates an example of a wrist-watch-type portableinformation terminal. The portable information terminal 7800 includes aband 7801, the display portion 7001, an input-output terminal 7802,operation buttons 7803, and the like. The band 7801 has a function of ahousing. A flexible battery 7805 can be included in the portableinformation terminal 7800. The battery 7805 may overlap with the displayportion 7001 and the band 7801, for example.

The band 7801, the display portion 7001, and the battery 7805 haveflexibility. Thus, the portable information terminal 7800 can be easilycurved to have a desired shape.

With the operation buttons 7803, a variety of functions such as timesetting, ON/OFF of the power, ON/OFF of wireless communication, settingand cancellation of silent mode, and setting and cancellation of powersaving mode can be performed. For example, the functions of theoperation buttons 7803 can be set freely by the operating systemincorporated in the portable information terminal 7800.

By touching an icon 7804 displayed on the display portion 7001 with afinger or the like, application can be started.

The portable information terminal 7800 can employ near fieldcommunication conformable to a communication standard. In that case, forexample, mutual communication between the portable information terminaland a headset capable of wireless communication can be performed, andthus hands-free calling is possible.

The portable information terminal 7800 may include the input-outputterminal 7802. In the case where the input-output terminal 7802 isincluded in the portable information terminal 7800, data can be directlytransmitted to and received from another information terminal via aconnector. Charging through the input-output terminal 7802 is alsopossible. Note that charging of the portable information terminaldescribed as an example in this embodiment can be performed bycontactless power transmission without using the input-output terminal.

FIGS. 54A to 54C illustrate an example of a watch-type foldable portableinformation terminal. A portable information terminal 7900 includes adisplay portion 7901, a housing 7902, a housing 7903, a band 7904, anoperation button 7905, and the like.

The portable information terminal 7900 can be reversibly changed inshape from a state in which the housing 7902 overlaps with the housing7903 as illustrated in FIG. 54A into a state in which the displayportion 7901 is opened as illustrated in FIG. 54C by lifting the housing7902 as illustrated in FIG. 54B. Therefore, the portable informationterminal 7900 can be generally used in a state where the display portion7901 is folded and can be used in a wide display region by developingthe display portion 7901.

When the display portion 7901 functions as a touch panel, the portableinformation terminal 7900 can be operated by touching the displayportion 7901. The portable information terminal 7900 can be operated bypushing, turning, or sliding the operation button 7905 vertically,forward, or backward.

A lock mechanism is preferably provided so that the housing 7902 and thehousing 7903 are not detached from each other accidentally whenoverlapping with each other as illustrated in FIG. 54A. In that case, itis preferable that the lock state can be canceled by pushing theoperation button 7905, for example. Alternatively, the lock state may becanceled by utilizing restoring force of a spring or the like as amechanism in which the portable information terminal is automaticallychanged in form from the state illustrated in FIG. 54A into the stateillustrated in FIG. 54C. Alternatively, the position of the housing 7902relative to the housing 7903 may be fixed by utilizing magnetic forceinstead of the lock mechanism. By utilizing magnetic force, the housing7902 and the housing 7903 can be easily attached or detached. Forexample, one of the housing 7902 and the housing 7903 is provided with aferromagnet, and the other thereof is provided with a magnet such as aferromagnet or a paramagnet so that the latter magnet overlaps with theformer ferromagnet when the two housings overlap with each other.

Although the display portion 7901 can be opened in a directionsubstantially perpendicular to the bending direction of the band 7904 inFIGS. 54A to 54C, the display portion 7901 may be opened in a directionsubstantially parallel to the bending direction of the band 7904 asillustrated in FIGS. 54D and 54E. In that case, the display portion 7901may be used in a bent state to be wound to the band 7904.

The electronic devices in this embodiment each include a display portionfor displaying some kind of information. The display panel, the touchpanel, the touch panel module, or the like of one embodiment of thepresent invention can be used for the display portion.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

This application is based on Japanese Patent Application serial no.2015-107248 filed with Japan Patent Office on May 27, 2015, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A touch panel comprising: pixels arranged in amatrix along a first direction and a second direction intersecting thefirst direction in a plan view; a signal line extending in the firstdirection; a scan line extending in the second direction; a first wiringcomprising a plurality of first portions extending in the firstdirection; a second wiring comprising a plurality of second portionsextending in the second direction; a third wiring along the firstwiring; and a fourth wiring along the second wiring, wherein: a bottomsurface of each of the first wiring and the third wiring is on the samesurface as one of a bottom surface of the signal line and a bottomsurface of the scan line, a bottom surface of each of the second wiringand the fourth wiring is on the same surface as the other of the bottomsurface of the signal line and the bottom surface of the scan line, thefirst wiring has a first stripe formed of the plurality of firstportions, the second wiring has a second stripe formed of the pluralityof second portions, a mesh shape formed of the first stripe and thesecond stripe is provided so as to surround the pixels one by one, andeach of the third wiring and the fourth wiring is in an electricallyfloating state.
 2. The touch panel according to claim 1, wherein thefirst wiring does not intersect the signal line in a region overlappingwith the pixels, and wherein the second wiring does not intersect thescan line in a region overlapping with the pixels.
 3. The touch panelaccording to claim 1, wherein the first wiring, the third wiring, andone of the signal line and the scan line are formed of a firstconductive film, and wherein the second wiring, the fourth wiring, andthe other of the signal line and the scan line are formed of a secondconductive film.
 4. The touch panel according to claim 1, furthercomprising a liquid crystal element, wherein the liquid crystal elementcomprises a pixel electrode, a liquid crystal, and a common electrode.5. The touch panel according to claim 4, further comprising: a firstsubstrate; a second substrate; a first polarizing plate; a secondpolarizing plate; and a backlight, wherein the backlight, the firstpolarizing plate, the first substrate, the second substrate, and thesecond polarizing plate are stacked in this order, and wherein thesignal line, the scan line, the first wiring, the second wiring, and thepixels are between the first substrate and the second substrate.
 6. Thetouch panel according to claim 1, further comprising a light-emittingelement, wherein the light-emitting element comprises a pixel electrode,an EL layer, and a common electrode.
 7. The touch panel according toclaim 6, further comprising: a first substrate; a second substrate; anda polarizing plate, wherein the polarizing plate, the first substrate,and the second substrate are stacked in this order, and wherein thesignal line, the scan line, the first wiring, the second wiring, and thepixels are between the first substrate and the second substrate.
 8. Thetouch panel according to claim 1, wherein the first wiring and thesecond wiring are configured to form a capacitor.
 9. The touch panelaccording to claim 1, wherein both the first wiring and the secondwiring are not overlapped with the pixels.
 10. The touch panel accordingto claim 1, wherein the one of the pixels surrounded by the mesh shapecomprises at least three sub-pixels of RGB.